Answer:
The toy's energy is 18 J.
Explanation:
We have, a 4 kg toy is lifted off the ground and falls at 3 m/s. It is required to find toy's energy.
The toy will have kinetic energy due to its motion. The energy is given by :
[tex]E=\dfrac{1}{2}mv^2\\\\E=\dfrac{1}{2}\times 4\times 3^2\\\\E=18\ J[/tex]
So, the toy's energy is 18 J.
In the figure calculates the acceleration of the block friction not today
Answer:
A fan pushes hot air out of a vent and into a room. The hot air displaces cold air in the room, causing the cold air to move closer to the floor.
The hot air displacing the cold air is an example of transfer by
Explanation:
Q1. What is the frequency of rotation of 1000 loop coil of area 20cm2 in a magnetic field of 5T to
generate an emf that has a maximum value of 15.7V?
Answer:
Explanation:
Emf e generated in a coil with no of turn n and area A rotating in a magnetic field B with angular speed of ω is given by the expression
e = e₀ sinωt
where e₀ = nωAB which is the maximum emf generated
Putting the given values
15.7 = 1000xω x 20 x 10⁻² x 5
ω = .0157
frequency of rotation
= ω / 2π
= .0157 / 2 x 3.14
= .0025 /s
9 rotation / hour .
A bowler releases a 7.0kg bowling ball from rest to a final velocity of 8.0m/s. What is the magnitude of the change in momentum of the bowling ball?
Answer:
56 kg m/s
Explanation:
Δp = mΔv
Δp = (7.0 kg) (8.0 m/s − 0 m/s)
Δp = 56 kg m/s
Electric motors convert electrical energy to mechanical energy. When the current-carrying coil is placed between the magnetic poles, a force acts on it that causes it to rotate. The image below shows a simple electric motor. The motor is used to lift metal boxes. How can the motor be changed to be able to lift a heavier box? A. rotate the coil in a counter-clockwise direction B. add more loops of wire between the magnets C. change the polarity of the magnet D. decrease the size of the magnets
Answer:
B. add more loops of wire between the magnets
Explanation:
this would increase the magnetic force acting on the rod therefore increasing
By adding more loops of wire between the magnets the motor is changed to be able to lift a heavier box.
What is an electric motor?An electric motor is a mechanism that turns electricity into mechanical energy.
The interaction between the motor's magnetic field and electric current in a wire winding generates force in the form of torque imparted to the motor's shaft in most electric motors.
An electric generator is physically equivalent to an electric motor, but it converts mechanical energy into electrical energy using a reversed flow of power.
The load capacity in the motor can be increased by increasing the no of loops. So by adding more loops of wire between the magnets the motor is changed to be able to lift a heavier box.
Hence option B is correct.
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The answers to the fill in the blank plz
Answer:
not too sure but i think it is : force - multiplied by -mass
19
Which gas is the most abundant greenhouse gas?
A.
ozone
B.
chlorofluorocarbon
C.
carbon dioxide
OD.
methane
E.
water vapor
Reset
Next
Carbon dioxide is the most abundant greenhouse gas in the atmosphere.
Answer:C
Explanation:
Carbon dioxide is the most abundance greenhouse gas in The atmosphere.
Which of the following is the healthiest type of carbohydrate?
A Bread made with white flour
B Rice made with whole grains
C Cereal made with refined grains
D White rice
Answer:
C
Explanation:
Cereal made with refined grains is the healthiest type of carbohydrate.
What are carbohydrates?
A carbohydrate is defined as a bio-molecule which consists of carbon,hydrogen and oxygen atoms which are usually in the ratio of 2:1 with the empirical formula C[tex]_n[/tex](H₂O)[tex]_n[/tex].
This term is most commonly used in field of biochemistry as a synonym of saccharide which is a group of sugars, starch and cellulose.
They perform various functions in living organisms. They serve as an energy source and as well as structural components . They are a key component in providing nutrition and are found in wide variety of natural as well as processed foods.
Carbohydrates occur as cellulose in the cell walls of plants and is one of the components of insoluble dietary fibers.
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A person jumps out a fourth-story window 14 m above a firefighter safety net. The survivor stretches the net 1.8 m before coming to rest. what was the deceleration experienced by the survivor? Use g = 9.8 m/s2 Calculate to one decimal.
Answer:
The deceleration is [tex]a = - 76.27 m/s^2[/tex]
Explanation:
From the question we are told that
The height above firefighter safety net is [tex]H = 14 \ m[/tex]
The length by which the net is stretched is [tex]s = 1.8 \ m[/tex]
From the law of energy conservation
[tex]KE_T + PE_T = KE_B + PE_B[/tex]
Where [tex]KE_T[/tex] is the kinetic energy of the person before jumping which equal to zero(because to kinetic energy at maximum height )
and [tex]PE_T[/tex] is the potential energy of the before jumping which is mathematically represented at
[tex]PE_T = mg H[/tex]
and [tex]KE_B[/tex] is the kinetic energy of the person just before landing on the safety net which is mathematically represented at
[tex]KE_B = \frac{1}{2} m v^2[/tex]
and [tex]PE_B[/tex] is the potential energy of the person as he lands on the safety net which has a value of zero (because it is converted to kinetic energy )
So the above equation becomes
[tex]mgH = \frac{1}{2} m v^2[/tex]
=> [tex]v = \sqrt{2 gH }[/tex]
substituting values
[tex]v = 16.57 m/s[/tex]
Applying the equation o motion
[tex]v_f = v + 2 a s[/tex]
Now the final velocity is zero because the person comes to rest
So
[tex]0 = 16.57 + 2 * a * 1.8[/tex]
[tex]a = - \frac{16.57^2 }{2 * 1.8}[/tex]
[tex]a = - 76.27 m/s^2[/tex]
I need help plz help me out 10 points!!!!!!!
Answer:
The answer is diffraction
Explanation:
Answer:
The answer is diffraction
Explanation:
I did the test! HOPE THIS HELPS!
Materials that allow electricity to pass through them are called ?
Answer:
Materials that allow electricity to pass through them are called conductors.
Copper wire is a good conductor. Materials that do not allow electricity to pass through them are called insulators.
Explanation:
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A cube, 1 m on each edge, is held 0.75 m below the surface of a pool of water by a rope. The mass of the cube is 700 kg, and the weight distribution is such that one face remains parallel to the surface of the water. a. Find the tension in the rope. b. Assuming the rope is cut, how far will the cube protrude from the water
Answer:
Explanation:
The mass of cube = 700 kg
volume = 1 m³
density = 700 kg / m²
Its density is less than that of water so it will try to float on the surface .
Tension in rope will be equal to net upward force
upthrust = volume x density of water x g
= 1 x 10³ x 9.8
= 9800 N
weight of cube = mass x g
= 700 x 9.8
= 6860 N .
Net upward force = 9800 - 6860
= 2940 N.
Tension in the rope = 2940 N.
Rope will hold the cube inside and not allow it to go outside water .
b )
If rope is cut , cube being lighter , will float on surface of water .
Part of cube inside water while floating
= 6860 / 9800
= .7
.7 m will remain inside water
part floating outside
= 1 - 0.7
= 0.3 m .
The figure shows a crane whose weight is 12.5 kN and center of gravity in G. (a) If the crane needs to suspend the 2.5kN drum, determine the reactions on the wheel in A and B when the boom is in the position shown.(b) Considering the same situation illustrated, what is the value of the maximum weight that the crane can suspend without tipping over?
Answer:
(a) Ra = 9.25 kN; Rb = 5.75 kN
(b) 26.7 kN
Explanation:
(a) Draw a free-body diagram of the crane. There are four forces:
Reaction Ra pushing up at A,
Reaction Rb pushing up at B,
Weight force 12.5 kN pulling down at G,
and weight force 2.5 kN pulling down at F.
Sum of moments about B in the counterclockwise direction:
∑τ = Iα
-Ra (0.66 m + 0.42 m + 2.52 m) + 12.5 kN (2.52 m + 0.42 m) − 2.5 kN ((3.6 m + 0.9 m) cos 30° − 2.52 m) = 0
-Ra (3.6 m) + 12.5 kN (2.94 m) − 2.5 kN (1.38 m) = 0
Ra = 9.25 kN
Sum of moments about A in the counterclockwise direction:
∑τ = Iα
Rb (0.66 m + 0.42 m + 2.52 m) − 12.5 kN (0.66 m) − 2.5 kN ((3.6 m + 0.9 m) cos 30° + 0.66 m + 0.42 m) = 0
Rb (3.6 m) − 12.5 kN (0.66 m) − 2.5 kN (4.98 m) = 0
Rb = 5.75 kN
Alternatively, you can use sum of the forces in the y direction as your second equation.
∑F = ma
Ra + Rb − 12.5 kN − 2.5 kN = 0
Ra + Rb = 15 kN
9.25 kN + Rb = 15 kN
Rb = 5.75 kN
However, you must be careful. If you make a mistake in the first equation, it will carry over to this equation.
(b) At the maximum weight, Ra = 0.
Sum of the moments about B in the counterclockwise direction:
∑τ = Iα
12.5 kN (2.52 m + 0.42 m) − F ((3.6 m + 0.9 m) cos 30° − 2.52 m) = 0
12.5 kN (2.94 m) − F (1.38 m) = 0
F = 26.7 kN
Alan leaves Los Angeles at 8:00 A.M. to drive to San Francisco 400 mi away. He manages to travel at a steady 50 mph in spite of traffic. Beth leaves Los Angeles at 9:00 A.M. and surprisingly manages to also drive at a constant speed, in this case 60 mph. (Knight 2.1) a. Who gets to San Francisco first? (Beth) b. How long does the first to arrive have to wait for the second? (20 minutes)
Answer:
a) Beth will reach before Alan
b)Beth has to wait 20 min for Alan to arrive
Explanation:
let 'd' be distance b/w Los Angeles and San Francisco i.e 400 mi
considering ,
Alan's speed [tex]v_A[/tex]=50mph
Beth's speed [tex]v_B[/tex]=60mph
->For Alan:
The time required [tex]t_A[/tex]= d/[tex]v_A[/tex]= 400/50 => 8h
-> For beth:
The time required [tex]t_B=\frac{d}{v_B} =\frac{400}{60} =>6\frac{2}{3} h[/tex] => 6h 40m
Alan will reach at 8:00 a.m +8h = 4:00p.m.
Beth will reach at 9:00 a.m +6h 40m= 3:40p.m.
a) Beth will reach before Alan
b)Beth has to wait 20 min for Alan to arrive
(10 points) A spring with a 7-kg mass and a damping constant 12 can be held stretched 1 meters beyond its natural length by a force of 4 newtons. Suppose the spring is stretched 2 meters beyond its natural length and then released with zero velocity. In the notation of the text, what is the value c2−4mk? m2kg2/sec2 Find the position of the mass, in meters, after t seconds. Your answer should be a function of the variable t of the form c1eαt+c2eβt where α= (the larger of the two) β=
Answer:
......................
In later years, motors improved and could be run directly from a 60 Hz power supply. As a result, 25 Hz power systems shrank and disappeared. However, there were many perfectly-good working 25 Hz motors in factories around the country that owners were not ready to discard. To keep them running, some users created their own 25 Hz power in the plant using motor-generator sets. A motor generator set consists of two machines connected on a common shaft, one acting as a motor and the other acting as a generator. If the two machines have different numbers of poles but exactly the same shaft speed, then the electrical frequency of the two machines will be different due to Equation (3-34). What combination of poles on the two machines could convert 60 Hz power to 25 Hz power?
Answer:
as in motor generaror are connected to same shaft then both machines are working with same speed
but number of poles are different with same speed means both machines are working with different frequencies
we know
frequency F = N*P/120
speed N = 82120F/P
given
motor speed = generator speed
120F1/P1 = 120F2/P2
F1/P1 = F2/P2
output frequency is 25 which is obtained from generator so F2=25
input frequency is 60 which is given to motor soF1=60
60/P1 = 25/P2
60/25 = P!/P2
P1/P2 = 12/5
multiply and divided by 2 becuase poles are even
P1/P2 = 12*2/5*2
=24/10
P1= 24 poles a
P2 =10 poles we get 25 hz frequency from 60 hz frequency
) Consider a beam of light traveling from a medium with a low index of refraction n1 to a new medium with a higher index of refraction n2. Use Snell’s Law to explain why total internal reflection will never occur in this situation, regardless of the choice of the incident angle.
Answer:
Snell's law says that
n1*sin(a1) = n2*sin(a2)
n1 < n2
son n2/n1 > 1
then:
sin(a1) = (n2/n1)sin(a2)
the maximum possible value of sin(x) is 1 when x =90°
total internal reflection means that a2= 90°
but as the coefficient that is multiplying sin(a2) is bigger than 1, we can not have a2 = 90°, because the right side will be greater than 1 and the left side can not be bigger than 1, so we can not have a2 = 90°, so we can not have total internal reflection
The maximum possible value of sin(x) is 1 when x =90°total internal reflection means that a2= 90°.
What is snell's law?Snell's law asserts that the ratio of the sines of the angle of incidence 1 and angle of refraction 2 for a given set of media is equal to the ratio of phase velocities (v1 / v2) in the two media, or equivalently, the refractive indices (n2 / n1).
If n1*sin(a1) = n2*sin(a2) and n1 n2 son n2/n1 > 1 according to Snell's law, then:
(n2/n1)sin = sin(a1) (a2)
When x =90°, the maximum feasible value of sin(x) is 1.
Total internal reflection indicates a2=90°, but because the coefficient multiplying sin(a2) is more than 1, we can't have a2 = 90° because the right side will be greater than 1 and the left side will be smaller than 1, therefore we can't have a2 = 90°. so we dont have total reflection.
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Dogs keep themselves cool by panting, rapidly breathing air in and out. Panting results in evaporation from moist tissues of the airway and lungs, which cools the animal. Measurements show that, on a 35∘C day with a relative humidity of 50%, a 12 kg dog loses 1.0 g of water per minute if it is panting vigorously. What rate of heat loss, in watts, does this achieve?
The rate of heat loss, in watts, does this achieve is 37.66 W
Evaporation:It leads in cooling since water absorbs heat equivalent to mass times latent heat of evaporation to get converted into vapor .
So,
latent heat of evaporation of water = 2260 x 10³ J / kg or 2260 J / g
Now
in the evaporation of 1 g of water , heat lost = 2260 J
And,
heat lost per minute = 2260 J
So,
heat lost per second = 2260 / 60
= 37.66 J /s
= 37.66 W
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A 0.025-kg block on a horizontal frictionless surface is attached to an ideal massless spring whose spring constant is The block is pulled from its equilibrium position at x = 0.00 m to a displacement x = +0.080 m and is released from rest. The block then executes simple harmonic motion along the horizontal x-axis. When the displacement is what is the kinetic energy of the block?
Complete Question
A 0.025-kg block on a horizontal frictionless surface is attached to an ideal massless spring whose spring constant is 150 N/m. The block is pulled from its equilibrium position at x = 0.00 m to a displacement x = +0.080 m and is released from rest. The block then executes simple harmonic motion along the horizontal x-axis. When the displacement is x = 0.024 m, what is the kinetic energy of the block?
Answer:
The kinetic energy is [tex]KE = 0.4368\ J[/tex]
Explanation:
From the question we are told that
The mass of the block is [tex]m= 0.025\ kg[/tex]
The spring constant is [tex]k = 150 N/m[/tex]
The length of first displacement is [tex]x_1 = 0.80 \ m[/tex]
The length of first displacement is [tex]x_2 = 0.024 \ m[/tex]
At the [tex]x_2[/tex] the kinetic energy is mathematically evaluated as
[tex]KE = \Delta E[/tex]
Where [tex]\Delta E[/tex] is the change in energy stored on the spring which is mathematically represented as
[tex]\Delta E = \frac{1}{2} k (x_1 ^2 - x_2^2)[/tex]
=> [tex]KE = \frac{1}{2} k (x_1 ^2 - x_2^2)[/tex]
Substituting value
[tex]KE = \frac{1}{2} * 150 * (0.08^2 - 0.024^2)[/tex]
[tex]KE = 0.4368\ J[/tex]
The voltage in a circuit is given by the equation V= IR.in this equation v is the voltage Iis correct and R is the resistance which answer shows this equation solved for current?
Answer:I=V/R
Explanation:
V=IR
Divide both sides by R
V/R=IR/R
V/R=I
I=V/R
The voltage in a circuit is given by the equation V= IR, in this equation v is the voltage Iis correct and R is the resistance the solution for the current is given as follows,
V= IR
I = V/R
What is resistance?Resistance is the obstruction of electrons in an electrically conducting material. The mathematical relation for resistance can be understood with the help of the empirical relation provided by Ohm's law.
V=IR
As for the given problem if we have to solve for the current from the equation V=IR
V=IR
I = V/R
Let us suppose a 60-volt battery connected in a closed circuit with a resistor of 15 ohms then we have o find out the amount of current flowing in the circuit,
Voltage = 60V
Resistance = 15 Ohm
Current =?
By using Ohm,s Law,
V=IR
I = V/R
By substituting the respective values,
I = 60/15
I = 4 Ampere
Hence, we solved for the current from the equation V=IR.
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A disk with a rotational inertia of 2.5 kg-m2 and a radius 1.1 m rotates on a frictionless fixed axis perpendicular to the disk faces and through its center. A force of 7.7 N is applied tangentially to the rim. The angular acceleration of the disk is _____ rad/s2. Round your answer to the nearest tenth.
Answer:
3.4 rad/sec^2
Explanation:
rotational inertia = 2.5 kg-m^2 radius = 1.1 m force = 7.7 N
t = rotational inertia * angular acceleration equation 1
also t = force * radius
therefore to calculate angular acceleration equation 1 becomes
f * r = inertia * angular acceleration hence
angular acceleration = f * r / inertia = [tex]\frac{7.7 * 1.1 }{2.5}[/tex] 8.47 / 2.5 = 3.388 ≈ 3.4 rad/sec^2
The Palo Verde nuclear power generator of Arizona has three reactors that have a combined generating capacity of 3.937×109 W . How many years would it take the Palo Verde nuclear power generator to produce the same amount of energy as the Sun does in one day? The energy generation rate, or luminosity, of the Sun is 3.839×1026 W
Answer:
t = 2.68 x 10¹⁴ years
Explanation:
First we need to find the amount of energy that Sun produce in one day.
Energy = Power * Time
Energy of Sun in 1 day = (3.839 x 10²⁶ W)(1 day)(24 hr/1 day)(3600 s/ 1 hr)
Energy of Sun in 1 day = 3.32 x 10³¹ J
Now, the time required by the nuclear power generator, in years, will be:
Energy of power generator = Energy Sun in 1 day = 3.32 x 10³¹ J
3.32 x 10³¹ J = Power * Time
3.32 x 10³¹ J = (3.937 x 10⁹ W)(t years)(365 days/1 year)(24 hr/1 day)(3600 s/ 1 hr)
t = 3.32 x 10³¹ /1.24 x 10¹⁷
t = 2.68 x 10¹⁴ years
Which of the following is not true about of the use of MRI in medicine?
1) It produces no negative side-effects on the human body
2) It produces high resolution images of soft tissues
3) It is very cheap
4) It requires very strong magnetic fields
Answer:
3) False. It is expensive since it requires sophisticated equipment and very low temperatures
Explanation:
Nuclear magnetic resonance imaging measurements consist of magnetic resonance imaging to analyze tissues by the transition of the unpaired electron at carbon 13, giving information on the structure and composition of tissues. This information is processed in computers and transformed into images.
So the physical measurement is the MRN
Now we can analyze the statements in the problem
1) True by itself a magnetic measurement is non-invasive
2) True. Measuring carbon transitions has information about the soft tissue of the body
3) False. It is expensive since it requires sophisticated equipment and very low temperatures
4) Right. The applied magnetic field is high to be able to induce carbon transaction
Describe the story of the constellation Capricornus. WILL MARK BRAINLEST IF NOT STOLEN FROM A WEBSITE OR ANYTHING WITH A PROPER ANSWER ASSAP
Your answer:
In Greek mythology, this constellation is related with the time the Olympian gods sought refuge in Egypt. Unfortunately, following their epic fighting with the Titans, peace did not closing for long, as the monster Typhon, son of the Titan Tartarus and Earth, sought revenge. Typhon was once a fearsome fire-breathing creature, taller than mountains and with palms which possessed dragons' heads in region of fingers. The Olympian gods sought to break out by way of adopting a number disguises: Zeus, a ram - Hera, a white cow, Bacchus (another model of the fable suggests Pan) a goat. As Typhon approached, Bacchus/Pan threw himself into the Nile but, in a panic, solely succeeded in altering part of his body, ending up with a goat's physique and the tail of a fish. Meanwhile, Zeus had been dismembered via Typhon, however was saved when Bacchus/Pan let out an ear-splitting yell, distracting the monster lengthy ample for an agile Hermes to gather the supreme god's limbs and cautiously fix him. In gratitude, Zeus transferred Bacchus/Pan to the heavens.
Answer:
Located in the Southern Hemisphere, Capricornus represents a creature that is a blend of fish and goat; the name means "goat horn" in Latin. While it is one of the Zodiac constellations identified by the Greek astronomer Ptolemy in the 2nd century, Capricornus is often used when referring to the constellation, while Capricorn is used in conjunction with the sign of the Zodiac.Locating Capricornus
Capricornus is among the faintest constellations, just brighter than Cancer. The 40th largest constellation, Capricornus measures 414 square degrees. It sits among the other constellations of the water genre, including the water-bearer Aquarius, the whale-like sea monster Cetus, the fishes Pisces, and the river Eridanus.
Right Ascension: 21.02 hours
Declination: -20 to -23 degrees
Visible: between latitudes 60 degrees and -90 degrees
Best viewed: During the month of September at 9 p.m.
To find the arrowhead-shaped Capricornus in the sky, look for the Summer Triangle and make a line from Vega through Altair to the lower southern sky.
The tropic of Capricorn the place where the sun appears overhead at noon on the winter solstice originally sliced right through its namesake constellation, but the line has since shifted to go through the constellation .
The constellation has its roots in the cultures of Sumeria — which identified it with a mythical figure that was half goat and half fish — and Babylonia, which portrayed it as a goat-human hybrid.
The Greeks associate the constellation with Pan, the god of nature. Part of Pan's lore was that he helped Zeus fight the Titans to earn his spot in the heavens. He escaped the monster Typhon by jumping into the Nile, but only half of his body was submerged, so he was a fish in the part of his body that remained underwater. Other spins on the tale have the constellation associated with Amalthaea, the mythical goat that acted as a foster mother to Zeus as an infant.
A 645 g block is released from rest at height h0 above a vertical spring with spring constant k = 530 N/m and negligible mass. The block sticks to the spring and momentarily stops after compressing the spring 14.9 cm. How much work is done (a) by the block on the spring and (b) by the spring on the block? (c) What is the value of h0? (d) If the block were released from height 3h0 above the spring, what would be the maximum compression of the spring?
Answer:
a)5.88J
b)-5.88J
c)0.78m
d)0.24m
Explanation:
a) W by the block on spring is given by
W= [tex]\frac{1}{2}[/tex]kx² = [tex]\frac{1}{2}[/tex](530)(0.149)² = 5.88 J
b) Workdone by the spring = - Workdone by the block = -5.88J
c) Taking x = 0 at the contact point we have U top = U bottom
So, mg[tex]h_o[/tex] = [tex]\frac{1}{2}[/tex]kx² - mgx
And, [tex]h_o[/tex]= ( [tex]\frac{1}{2}[/tex]kx² - mgx )/(mg) = [tex][\frac{1}{2} (530)(0.149^2)-(0.645)(9.8)(0.149)[/tex]]/(0.645x9.8)
[tex]h_o[/tex]= 0.78m
d) Now, if the initial initial height of block is 3[tex]h_o[/tex]
[tex]h_o[/tex] = 3 x 0.78 = 2.34m
then, [tex]\frac{1}{2}[/tex]kx² - mgx - mg[tex]h_o[/tex] =0
[tex]\frac{1}{2}[/tex](530)x² - [(0.645)(9.8)x] - [(0.645)(9.8)(2.34) = 0
265x² - 6.321x - 14.8 = 0
a=265
b=-6.321
c=-14.8
By using quadratic eq. formula, we'll have the roots
x= 0.24 or x=-0.225
Considering only positive root:
x= 0.24m (maximum compression of the spring)
The throwing back by a wall or barrier of a sound wave without absorbing
it. *
1 point
Answer:Reflection
Explanation:
The throwing back of a sound wave without absorbing it is called reflection
In acoustic reflection of sound is termed as echo i.e. sound arrived at the listener after a particular delay depending upon the position of barrier to the observer.
The reflection of sound is used in many devices like megaphone, trumpets, etc. It is also used in auditorium such that the ceiling of the auditorium is curved for multiple reflections of sound so that sound can be reached at every corner of the auditorium.
Serena Williams consistently serves a tennis ball with a top speed of 128 mph. The ball is accelerated essentially from rest (assume v0 = 0 mph) to top speed while it is in contact with the racket for 5 milliseconds. LaTeX: a=\frac{\left(vf-vo\right)}{t}a = ( v f − v o ) t Where a is the acceleration, vf is the final (top) velocity, v0 is the initial velocity, and t is time. If the mass of the average tennis ball is 5.85 g, what force must Serena exert on the ball during that time to achieve the required acceleration, in units of Newtons?
Answer:
66.94N
Explanation:
To find the force you use the second Newton law, which is given by:
[tex]F=ma[/tex] (1)
m: mass of the ball 5.85g
the acceleration is:
[tex]a=\frac{v_f-v_o}{t}[/tex]
vf: final velocity = 128mph = 57.21m/s
vo : initial velocity = 0m/s
t: time = 5ms =5*10^{-3}s
by computing the acceleration and replacing it in the equation (1) you obtain:
[tex]a=\frac{57.21m/s}{5*10^{-3}s}=11443.2\frac{m}{s^2}\\\\F=(5.85*10^{-3}kg)(11443.20m/s^2)=66.94N[/tex]
hence, the force applied by Serena on the ball is 66.94N
As SCUBA divers go deeper underwater, the pressure from the weight of all the water above them increases tremendously which compresses the gases in their blood. What happens to the volume of gas in their blood as the diver rises quickly to the surface?
Answer:
The volume of gas in an early diving bell full of air at sea level is halved at 10 m according to Boyle’s law
Explanation:
;at 20 m pressure is 300 kPa absolute and the gas is compressed into one third the volume.
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Potassium is a crucial element for the healthy operation of the human
body. Potassium occurs naturally in our environment (and thus our
bodies) as three isotopes: Potassium-39, Potassium-40, and Potassium-
41. Their current abundances are 93.26%, 0.012% and 6.728%. A typical
human body contains about 3.0 grams of Potassium per kilogram of body
mass.
1. How much Potassium-40 is present in a person with a mass of 80
kg?
2. If, on average, the decay of Potassium-40 results in 1.10 MeV of
energy absorbed, determine the effective dose (in Sieverts) per year
due to Potassium-40 in an 80-kg body. Assume an RBE of 1.2. The
half-life of Potassium-40 is 1.28 x 10° years.
Geologists have divided rocks into three different categories based on ______
A tennis player serves a tennis ball such that it is moving horizontally when it leaves the racquet. When the ball travels a horizontal distance of 13 m, it has dropped 56 cm from its original height when it left the racquet. What was the initial speed, in m/s, of the tennis ball
Answer:
The initial velocity is 38.46 m/s.
Explanation:
The horizontal distance travel by the tennis ball = 13 m
The height at which the tennis ball dropped = 56 cm
Now calculate the initial speed of tennis ball.
The vertical velocity is zero.
Below is the calculation. Here, first convert centimetre into kilometre. So, height at which ball dropped is 0.56 km.
[tex]v = \sqrt{2 \times 9.8 \times 0.56} = 3.32 m/s \\[/tex]
[tex]t = \frac{3.32}{9.8} = 0.338s \\[/tex]
[tex]Ux \times t = 13 \\[/tex]
[tex]Ux = \frac{13}{0.338} = 38.46 m/s = Initial velocity.[/tex]
