Answer:
45 s .
Explanation:
The accelerator will first accelerate , then move with uniform velocity and at last it will decelerate to rest .
displacement s = ?
acceleration a = 1 m /s²
Final speed v = 5 m/s
initial speed u = 0
v² = u² + 2as
5² = 0 + 2 x 1 x s
s = 12.5 m
B) Let time of acceleration or deceleration be t
v = u + a t
5 = 0 + 1 t
t = 5 s
Similarly displacement during deceleration = 12.5 m
Total distance during uniform motion = 200 - ( 12.5 + 12.5 ) = 175 m .
velocity of uniform motion = 5 m /s
time during which there was uniform velocity = 175 / 5 = 35 s
Total time = 5 + 35 + 5 = 45 s .
You are playing with a yoyo . If Potential energy of the yoyo is 18 J , and the total mechanical energy is 20 J , how much kinetic energy does the yoyo have ?
Answer:
the kinetic energy of the yoyo is 2 J.
Explanation:
Given;
potential energy of yoyo, P.E = 18 J
total mechanical energy, M.E = 20 J
The kinetic energy of yoyo is calculated as;
M.E = K.E + P.E
where;
K.E is the kinetic energy
K.E = M.E - P.E
K.E = 20 J - 18 J
K.E = 2 J
Therefore, the kinetic energy of the yoyo is 2 J.
Why is deforestation a serious global environment problem
Answer:
we all know that deforestation is when tress are cut down but this may cause cardio dioxide to go up into the atmosphere and this may cause the rise in sea level and temperates tend to fluctuate
Explanation:
I'm just that smart yah dig
What do you think would happen to the force of attraction of two interacting charges if their distance apart is halved?
Answer:
The new force becomes 4 times the initial force.
Explanation:
The force of attraction or repulsion is given by the relation as follows :
[tex]F=k\dfrac{q_1q_2}{d^2}[/tex]
Where
d is the distance between the interacting charges
F is inversely proportional to the distance between charges.
If the distance is halved, d'=(d/2), new force is given by :
[tex]F'=k\dfrac{q_1q_2}{d'^2}\\\\=k\dfrac{q_1q_2}{(\dfrac{d}{2})^2}\\\\=k\dfrac{q_1q_2}{\dfrac{d^2}{4}}\\\\=4\times \dfrac{kq_1q_2}{d^2}\\\\F'=4F[/tex]
So, the new force becomes 4 times the initial force.
Curtis, a student in our class, makes the following statement: The puck reached a slightly higher location on the ramp than I predicted. This is because I used the wrong mass for the puck when I did all my calculations. I accidentally used the mass of the smaller puck rather than the mass of the larger puck in my video." Is this a plausible explanation? Would the using the wrong mass for the puck during the calculations mean the puck would reach a greater height? Explain your reasoning.
Answer and Explanation: No, the explanation is not plausible. The puck sliding on the ice is an example of the Principle of Conservation of Energy, which can be enunciated as "total energy of a system is constant. It can be changed or transferred but the total is always the same".
When a player hit the pluck, it starts to move, gaining kinetic energy (K). As it goes up a ramp, kinetic energy decreases and potential energy (P) increases until it reaches its maximum. When potential energy is maximum, kinetic energy is zero and vice-versa.
So, at the beginning of the movement the puck only has kinetic energy. At the end, it gains potential energy until its maximum.
The representation is as followed:
[tex]K_{i}+P_{i}=K_{f}+P_{f}[/tex]
[tex]K_{i}+0=0+P_{f}[/tex]
[tex]\frac{1}{2}mv^{2} = mgh[/tex]
As we noticed, mass of the object can be cancelled from the equation, making height be:
[tex]h=\frac{v^{2}}{2g}[/tex]
So, the height the puck reaches depends on velocity and acceleration due to gravity, not mass of the puck.
which experimental result led to a revision of Thomas's plum pudding model of the atom?
A. electrons were found to have higher energy the farther they are from the nucleus
B. the beam in a cathode ray tube was moved by an electric force
C. A few alpha particles bounced off a thin sheet of gold foil
D. most alpha particles passed straight through a thin sheet of gold foil
Answer: C. A few alpha particles bounced off a thin sheet of gold foil.
Two steamrollers begin 105 mm apart and head toward each other, each at a constant speed of 1.20 m/s. At the same instant, a fly that travels at a constant speed of 2.50 m/s starts from the front roller of the southbound steamroller and flies to the front roller of the northbound one, then turns around and flies to the front roller of the southbound once again, and continues in this way until it is crushed between the steamrollers in a collision.
Required:
What distance does the fly travel?
Answer: 109.4 mm
Explanation: Distance is a scalar quantity and it is the measure of how much path there are between two locations. It can be calculated as the product of velocity and time: d = vt
The separation between the two steamrollers is 105 mm or 0.105 m. They collide to each other at the middle of the separation:
location of collision = [tex]\frac{0.105}{2}[/tex] = 0.0525 m
To reach that point, both steamrollers will have spent
[tex]v=\frac{\Delta x}{t}[/tex]
[tex]t=\frac{\Delta x}{v}[/tex]
[tex]t=\frac{0.0525}{1.2}[/tex]
t = 0.04375 s
The fly is travelling with speed of 2.5 m/s. So, at t = 0.04375 s:
d = 2.5*0.04375
d = 0.109375 m
Until it is crushed, the fly will have traveled 109.4 mm.
Energy from the Sun is transferred from the Earth’s surface to the atmosphere, resulting in
atmospheric convection currents that produce winds. How do physical properties of the air
contribute to convection currents?
a -The warmer air sinks because it is more dense than cooler air.
b -The warmer air rises because it is more dense than cooler air.
c- The warmer air sinks because it is less dense than cooler air.
d -The warmer air rises because it is less dense than cooler air.
The _______ changes light energy into nerve signals using receptors called rods and cones. A. retina B. lens C. iris D. pupil
Answer:
A. Retina
Explanation:
A ball of mass m makes a head-on elastic collision with a second ball (at rest) and rebounds in the opposite direction with a speed equal to one-fourth its original speed. what is the mass of the second ball?
When a ball of mass m makes a head-on elastic collision with a second ball (at rest) and rebounds in the opposite direction with a speed equal to one-fourth its original speed, then mass of the second ball having v/3 is velocity after collision is 9m/4.
What is momentum ?Momentum is defined as mass times velocity of body. it is denoted by p and its SI unit is Kg.m/s. It has both magnitude and direction. it is a vector quantity. it tells about the moment of the body. it is denoted by p and expressed in kg.m/s. mathematically it is written as p = mv. A body having zero velocity or zero mass has zero momentum. its dimensions is [M¹ L¹ T⁻¹]. Momentum is conserved throughout the motion.
initial momentum = final momentum
Given,
mass of first body m₁ = m
initial velocity of first body = v₁' = v
final velocity of first body = v₁'' =v/4
mass of second body m₂ = ?
initial velocity of second body = v₂' = 0
final velocity of second body = v₂'' = v/3
According to conservation of momentum,
initial momentum = final momentum
m₁v₁' + m₂v₂' = m₁v₁'' + m₂v₂''
putting al above values
m₁v + 0 = m₁v/4 + m₂v/3
m₁v - m₁v/4 = m₂v/3
m (1 - 1/4)v = m₂v/3
3m/4 = m₂/3
m₂ = 9m/4
Hence mass of the second body is 9m/4.
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The 49-g arrow is launched so that it hits and embeds in a 1.45 kg block. The block hangs from strings. After the arrow joins the block, they swing up so that they are 0.44 m higher than the block's starting point.
Required:
How fast was the arrow moving before it joined the block?
Answer:
the initial speed of the arrow before joining the block is 89.85 m/s
Explanation:
Given;
mass of the arrow, m₁ = 49 g = 0.049 kg
mass of block, m₂ = 1.45 kg
height reached by the arrow and the block, h = 0.44 m
The gravitational potential energy of the block and arrow system;
P.E = mgh
P.E = (1.45 + 0.049) x 9.8 x 0.44
P.E = 6.464 J
The final velocity of the system after collision is calculated as;
K.E = ¹/₂mv²
6.464 = ¹/₂(1.45 + 0.049)v²
6.464 = 0.7495v²
v² = 6.464 / 0.7495
v² = 8.6244
v = √8.6244
v = 2.937 m/s
Apply principle of conservation of linear momentum to determine the initial speed of the arrow;
[tex]P_{initial} = P_{final}\\\\mv_{arrow} + mv_{block} = (m_1 + m_2)V\\\\0.049(v) + 1.45(0) = (0.049 + 1.45)2.937\\\\0.049v = 4.4026\\\\v = \frac{4.4026}{0.049} \\\\v = 89.85 \ m/s[/tex]
Therefore, the initial speed of the arrow before joining the block is 89.85 m/s
The arrow moving as the speed of "76.36 m/s".
According to the question,
By using the conservation of energy, we have
→ [tex]K.E=P.E[/tex]
→ [tex]\frac{1}{2} (m_1+m_2)v_2^2= (m_1+m_2)gh[/tex]
or,
→ [tex]v_2 = \sqrt{2mgh}[/tex]
By substituting the values, we have
→ [tex]= \sqrt{2\times 9.8\times 0.44}[/tex]
→ [tex]=2.469 \ m/s[/tex]
Now,
By using the conservation of momentum, we get
→ [tex]m_1 v_1 = (m_1+m_2) v_2[/tex]
or,
→ [tex]v_1 = \frac{(m_1+m_2)v_2}{m_1}[/tex]
[tex]= \frac{1.45+0.049}{0.049}\times 2.469[/tex]
[tex]= 30.6\times 2.496[/tex]
[tex]= 76.36 \ m/s[/tex]
Thus the above approach is correct.
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A car traveling west at 15 m/s and speeds up to 20 m/s west in 5 seconds. Why is the acceleration of the car?
Answer:
1 m/s
Explanation:
5m/s change in velocity, divided by 5 seconds= 1 meter/second/second
change in velocity/change in time
Acceleration = (change in velocity) / (time for the change)
that's = (change in speed and its direction) / (time for the change)
Change in velocity = (ending velocity) - (starting velocity)
Change in velocity = (20 m/s west) - (15 m/s west)
Change in velocity = 5 m/s west
Acceleration = (5 m/s west) / (5 seconds)
Acceleration = 1 m/s west
At baseball practice, Mason and Alfredo both picked up the same bat and neither would let go until one of them had it for himself. Mason pulled the bat with
force of 15 newtons (N) while Alfredo pulled with a force of 20 newtons (N). Why did Alfredo end up with the bat?
A because the force was 5 N in Mason's direction
B. O because the net force was 5 N in Alfredo's direction
c. O because the net force was 15 N in Mason's direction
D.O because the net force was 20 N in Alfredo's direction
Answer:
Option B. O because the net force was 5 N in Alfredo's direction
Explanation:
To know the the correct answer to the question given above, we shall determine the net force acting on the bat. This can be obtained as follow:
Force of pull by Mason (Fₘ) = 15 N
Force of pull by Alfredo (Fₐ) = 20 N
Net force (Fₙ) =?
Fₙ = 20 – 15
Fₙ = 5 N in Alfredo's direction
From the calculation made above, we can see that the net force is 5N in Alfredo's direction. This is the reason why Alfredo end up having the bat.
Name and explain the
various types of friction.
Answer:
There are four types of friction: static, sliding, rolling, and fluid friction. Static, sliding, and rolling friction occur between solid surfaces. Static friction is strongest, followed by sliding friction, and then rolling friction, which is weakest. Fluid friction occurs in fluids, which are liquids or gases.
Explanation:
This table shows the mass and volume of four different objects.
A two-column table with 4 rows. The first column titled objects has entries W, X, Y, Z. The second column titled Measurements has entries Mass: 16 grams Volume: 84 centimeters cubed in the first cell, Mass: 12 grams Volume: 5 centimeters cubed in the second cell, Mass: 4 grams Volume: 6 centimeters cubed in the third cell, Mass: 408 grams Volume: 216 centimeters cubed in the fourth cell.
Which ranks the objects from most to least dense?
Answer:
Here its right but its also better than Barney's response
Explanation:
W, Y, Z, X or C
Answer:
W, Y, Z, X
Explanation:
Einstein's equivalence principle says that __________. Einstein's equivalence principle says that __________. everyone measures the speed of light to be equivalent someone traveling at 0.9c will age at the same rate as someone at 0.99c all people see themselves at an equivalent distance to the center of the universe the effects of gravity are exactly equivalent to the effects of acceleration
Answer:
Einstein's equivalence principle says that __________.
the effects of gravity are exactly equivalent to the effects of acceleration
Explanation:
The equivalence principle is one of the fundamental laws of physics, as enunciated by Einstein. It categorically states that the gravitational and inertial forces are of a similar nature. In physics, a gravitational acceleration is the acceleration of an object in a free fall within a space. The importance of Einstein's Equivalence Principle is explained by his theory of general relativity. This theory states that mass is the same, whether inertial or gravitational.
According to the Einstein's equivalence principle, the effects of gravity are exactly equivalent to the effects of acceleration.
Einstein's equivalence principle says that the effects of gravity are exactly equivalent to the effects of acceleration.
What is Einstein's equivalence principle?Einstein's equivalence principle states that the the force due to gravity and the force of inertia are similar in the nature and there is no need to distinct them.
The inertia force is opposite in direction to accelerating force of a body. Thus the Einstein's equivalence principle can also be stated as "the effects of gravity are exactly equivalent to the effects of acceleration." Form the given option the correct option which can be filled in the blank is option 2 which states that the effects of gravity are exactly equivalent to the effects of acceleration.Thus Einstein's equivalence principle says that the effects of gravity are exactly equivalent to the effects of acceleration.
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Consider a Carnot cycle executed in a closed system with 0.6 kg of air. The temperature limits of the cycle are 300 and 1100 K, and the minimum and maximum pressures that occur during the cycle are 20 and 3000 kPa. Assuming constant specific heats, determine the net work output per cycle.
Answer:
63.8 kJ
Explanation:
The net work output per cycle is the difference in heat input and heat output. The heat input and heat output are expressed as a function of volume ratios, while volume is expressed as a function of pressure and pressure as a function of temperature.
R = 287 J/kg.K, k = 1.4
Hence the net work input (W) is given as:
[tex]W=Q_{in}-Q_{out}\\\\W=mR[T_Hln\frac{V_2}{V_1} -T_Lln\frac{V_3}{V_4}]\\\\=mR[T_Hln\frac{P_1}{P_2} -T_Lln\frac{P_4}{P_3}]\\\\=mR[T_Hln(\frac{P_1}{P_3}(\frac{T_L}{T_H} )^\frac{k}{k-1}) -T_Lln(\frac{P_1}{P_3}(\frac{T_L}{T_H} )^\frac{k}{k-1})]\\\\=mR(T_H-T_L)ln(\frac{P_1}{P_3}(\frac{T_L}{T_H} )^\frac{k}{k-1})\\\\Substituting\ values:\\\\W=mR(T_H-T_L)ln(\frac{P_1}{P_3}(\frac{T_L}{T_H} )^\frac{k}{k-1})=0.6*287(1100-300)ln(\frac{3000*10^3}{2-*10^3}(\frac{300}{1100} )^\frac{1.4}{1.4-1})\\\\[/tex]
[tex]W=63.8\ kJ[/tex]
why do players choose to follow the unconventional route of kicking down the middle
Answer:
My biggest reason is to make it a habit. Even if the ball goes into the endzone it is a live ball and the offensive players must down the ball. Don't leave any room for "I thought he downed it" or "I thought I heard the whistle" just run to the ball always.
If the players slow down and the returner takes it out of the end zone it could be a big return. Players are on a full sprint for 40+ yards sometimes and instead of breaking down, they choose to contine through the goal line to slow down at a decreased rate (possibly limiting a muscle pull injury).
A person pushes down on a lever with a force of 100 N. At the other end of the lever, a force of 200 N lifts a heavy object. What is the mechanical advantage of the lever?
A. 1/2, because the object will be lifted half the distance
B. -1, because the direction changes
C. 2, because the output force is twice the input force
D. 1, because the same amount of work is done
Answer:
Explanation:
C 200÷100=2
Output ÷ Input= MA
What is Ex(P), the value of the x-component of the electric field produced by by the line of charge at point P which is located at (x,y) = (a,0), where a = 8.7 cm?
Answer:
The answer is below
Explanation:
We are going to use Gauss’ law to find the electric field equation. Since electric field is coming from an infinite line of charge, hence it is going out in a radial direction.
Therefore we use the area of the electric field which passes through, forming a Gaussian cylinder. We neglect the ends of the area.
Hence:
[tex]\int\limits {E} \, dA=\frac{Q_{enc}}{\epsilon_o}\\\\E(2\pi rL)= \frac{\lambda L}{\epsilon_o}\\\\E=\frac{\lambda}{2\pi r\epsilon_o} \\\\Given \ that:\\\\r=a=8.7\ cm=0.087\ m, \lambda=-2.3 \mu C/cm=-2.3*10^{-4}\ C/m,\epsilon_o=8.85*10^{-12}F/m.\\\\Hence:\\\\E=\frac{-2.3*10^{-4}}{2\pi *0.087*8.85*10^{-12}}=-4.75*10^7\ N/C[/tex]
The value of the x-component of the electric field is -475213.968 newtons per coulomb.
Procedure - Determination of the magnitude of an electric field at a given pointIn this question we shall apply Gauss' Law to determine the magnitude of the electric field ([tex]E_{x}[/tex]), in newtons per coulomb, rapidly and based on the assumptions of uniform charge distribution and cylindrical symmetry.
[tex]\frac{Q_{enc}}{\epsilon_{o}} = \oint\,\vec E\,\bullet d\vec A[/tex] (1)
Where:
[tex]Q_{enc}[/tex] - Enclosed charge, in coulombs.[tex]\epsilon_{o}[/tex] - Vacuum permitivity, in quartic second-square amperes per kilogram-cubic meter.[tex]\vec E[/tex] - Electric field vector, in newtons per coulomb.[tex]\vec A[/tex] - Area vector, in square meters.Based on all assumptions, we simplify (1) as follows:
[tex]\frac{\lambda\cdot l}{\epsilon_{o}} = E \cdot (2\pi\cdot r\cdot l)[/tex]
And the equation of the x-component of the electric field is:
[tex]E = \frac{\lambda}{2\pi\cdot \epsilon_{o}\cdot r}[/tex] (2)
Where [tex]\lambda[/tex] is the linear charge density, in coulomb per meter.
If we know that [tex]\lambda = -2.3\times 10^{-6}\,\frac{C}{m}[/tex] and [tex]a = 0.087\,m[/tex], then the electric field produced by the line of charge at point P is:
[tex]E = \frac{\left(-2.3\times 10^{-6}\,\frac{C}{m} \right)}{2\pi\cdot \left(8.854\times 10^{-12}\,\frac{s^{4}\cdot A^{2}}{kg\cdot m^{3}} \right)\cdot (0.087\,m)}[/tex]
[tex]E_{x} = -475213.968 \,\frac{N}{C}[/tex]
The value of the x-component of the electric field is -475213.968 newtons per coulomb. [tex]\blacksquare[/tex]
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Answer:
How can I help you??? Plz insert some questions
A car is traveling on a straight road at a constant 35 m/sm/s, which is faster than the speed limit. Just as the car passes a police motorcycle that is stopped at the side of the road, the motorcycle accelerates forward in pursuit. The motorcycle passes the car 13.5 ss after starting from rest. What is the acceleration of the motorcycle (assumed to be constant)
Answer:
2.59m/s
Explanation:
Using the equation of motion
v = u+at
v is the final velocity = 35ms
u is the initially velocity = 9m/s
t is the time = 13.5s
a is the acceleration
Substitute into the formula
35 = 0+13.5a
a = 35/13.5
a = 2.59m/s²
Hence the acceleration of the motorcycle is 2.59m/s
Anyone can help me out with this question ? Just number 2,
Answer:
- 21⁰C .
Explanation:
Speed of jet = 2.05 x 10³ km /h
= 2050 x 1000 / (60 x 60 ) m /s
= 569.44 m / s
Mach no represents times of speed of sound , the speed of jet
1.79 x speed of sound = 569.44
speed of sound = 318.12 m /s
speed of sound at 20⁰C = 343 m /s
Difference = 343 - 318.12 = 24.88⁰C
We know that 1 ⁰C change in temperature changes speed of sound
by .61 m /s
So a change in speed of 24.88 will be produced by a change in temperature of
24.88 / .61
= 41⁰C
temperature = 20 - 41 = - 21⁰C .
How much kinetic energy does a 0.104 kg hamster have if it is moving at 24.0 m/s?
Answer:
30J
Explanation:
Given parameters:
Mass of hamster = 0.104kg
Velocity = 24m/s
Unknown:
Kinetic energy = ?
Solution:
Kinetic energy is the energy due to the motion of a body. It is mathematically derived by;
Kinetic energy = [tex]\frac{1}{2}[/tex] m v²
m is the mass
v is the velocity
Kinetic energy = [tex]\frac{1}{2}[/tex] x 0.104 x 24² = 30J
What happens to kinetic energy when you decrease the velocity of a moving object?
1. A particle is projected vertically upwards with a velocity of 30 ms from a point 0. Find (a) the maximum height reached(b) the time taken for it to return to 0 (c) the taken for it to be 35m below 0
Assuming the particle is in free fall once it is shot up, its vertical velocity v at time t is
v = 30 m/s - g t
where g = 9.8 m/s² is the magnitude of the acceleration due to gravity, and its height y is given by
y = (30 m/s) t - 1/2 g t ²
(a) At its maximum height, the particle has 0 velocity, which occurs for
0 = 30 m/s - g t
t = (30 m/s) / g ≈ 3.06 s
at which point the particle's maximum height would be
y = (30 m/s) (3.06 s) - 1/2 g (3.06 s)² ≈ 45.9184 m ≈ 46 m
(b) It takes twice the time found in part (a) to return to 0 height, t ≈ 6.1 s.
(c) The particle falls 35 m below its starting point when
-35 m = (30 m/s) t - 1/2 g t ²
Solve for t to get a time of about t ≈ 7.1 s
A hazard sign has 3 identical
parallelogram-shaped stripes as shown.
Charles must outline each stripe with
reflective tape. Is one roll of 144 inches
of tape enough to finish the job?
Answer and Explanation: To know how much tape he will need, we have to calculate the perimeter of each parallelogram-shaped stripe.
Perimeter is the sum of all the sides of a figure.
For a parallelogram:
P = 2*length + 2*width
So, we need to determine width and length of the stripe.
Width is 3 inches. Length is the hypotenuse of the right triangle, whose sides are 6 and 18 inches. Then, length is
[tex]h=\sqrt{18^{2}+6^{2}}[/tex]
[tex]h=\sqrt{360}[/tex]
h = 19 in
Perimeter of the first stripe is
P = (2*19) + (2*3)
P = 44 inches
The hazard sign has 3 stripes. So total perimeter is
[tex]P_{t}=[/tex] 44 + 44 + 44
[tex]P_{t}=[/tex] 132 inches
To outline the parallelogram-shaped stripes, Charles need a total of 132 inches of tape. Since one roll has 144 inches, he will have enough tape to finish the job.
When a moving object collides with an object that isn't moving, what happens to the kinetic energy of each object?
All the objects are motionless, so kinetic energy of each object is zero after the collision.
What is Kinetic Energy?The kinetic energy of an object is defined as the energy which is possesses due to its motion. It is the work required to accelerate a body of a given mass from rest to its stated velocity. This energy is gained during its acceleration, the body maintains the kinetic energy as long as its momentum does not change.
Kinetic Energy can be expressed as
[tex]K.E.=[/tex] [tex]1/2 mv^2[/tex]
Where, m is the mass of the object
v is the velocity.
It is expressed in joules (J).
After the collision all the objects are at rest, therefore, the final kinetic energy is also zero which shows maximum loss of kinetic energy. Such collisions are called perfectly inelastic.
Thus, all the objects are motionless, so kinetic energy of each object is zero after the collision.
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A fish finder uses a sonar device that sends 20,000-Hz sound pulses downward from the bottom of the boat, and then detects echoes. If the maximum depth for which it is designed to work is 85 m, what is the minimum time between pulses (in fresh water)?
Answer:
0.3106 seconds
Explanation:
Frequency= 20,000-Hz
The speed of echoes sounds can be calculated using the expression below;
Y= ( 2x/t) ...........................eqn(1)
t= overall time taken
x = maximum depth = 230m
Y= speed of echoes sounds
Speed of sound in water= 1,481 m/s which is a constant with little variation.
If we substitute the given values into eqn(1) we have
1481 = (2× 230)/ t
1481 × t= 460
t=460/1481
t=0.3106 seconds
Hence, the minimum time between pulses (in fresh water) is 0.3106 seconds
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Explain the movement of a roller coaster in terms of potential and kinetic energy? When are these energies thegreatest? Smallest? Are they ever the same?
Answer:
Potential energy: Greatest at the top of the hill
Kinetic energy: Greatest at the bottom of the hill
The two meet at some point on the way down!
Explanation:
Potential energy is energy that represents an object's potential for motion. Kinetic energy is that object's energy during motion. They're two sides of the same coin, and in fact, their sum gets a special name: mechanical energy. Potential energy builds up in reaction to working against certain forces - in the case of the roller coaster, that primary force is gravity. Gravity exerts a downward force on the roller coaster, and it takes work to pull it up the hill.
When it reaches the peak, the coasters potential energy is at its highest, and the moment it crests over the hill and begins its descent, that gravitational potential energy starts converting into kinetic energy: the coaster starts accelarating down the track, and the potential energy decreases at the same rate that the kinetic energy increases.
At the bottom of the hill, all of that potential energy has become kinetic energy, and the coaster zooms along the track, hopefully not giving too many riders nausea
a block of mas \( m \) = 4.8 kg slides head on into a spring of spring constant \( k \) = 430 N/m. When the block stops, it has compressed the spring by 5.8 cm. The coefficient of kinetic friction between block and floor is 0.28. \( (g =9.8m/s^2) \)
Answer:
See explanation below
Explanation:
The question is incomplete. The missing part of this question is the following:
"While the block is in contact with the spring and being brought to rest, what are (a)the work done by the spring force and (b) the increase in thermal energy of the blockfloor system? (c) What is the blocks speed just as it reaches the spring?"
According to this we need to calculate three values: Work, Thermal Energy and Speed of the block when it reaches the spring.
Let's do this by parts.
a) Work done by the spring:
In this case, we need to apply the following expression:
W = -1/2 kx² (1)
We know that k = 430 N/m, and x is the distance of compressed spring which is 5.8 cm (or 0.058 m). Replacing that into the expression:
W = -1/2 * 430 * (0.058)²
W = -0.7233 Jb) Increase in thermal energy
In this case we need to use the following expression:
ΔEt = Fk * x (2)
And Fk is the force of the kinetic energy which is:
Fk = μk * N (3)
Where μk is the coeffient of kinetic friction
N is the normal force which is the same as the weight, so:
N = mg (4)
Let's calculate first the Normal force (4), then Fk (3) and finally the chance in the thermal energy (2):
N = 4.8 * 9.8 = 47.04 N
Fk = 0.28 * 47.04 = 13.1712 N
Finally the Thermal energy:
ΔEt = 13.1712 * 0.058
ΔEt = 0.7639 Jc) Block's speed reaching the spring
As the block is just reaching the speed, the initial Work is 0. And the following expression will help us to get the speed:
V = √2Ki/m (5)
And Ki, which is the initial kinetic energy can be calculated with:
Ki = ΔU + ΔEt (6)
And ΔU is the same value of work calculated in part (a) but instead of being negative, it will be positive here. So replacing the data first in (6) and then in (5), we can calculate the speed:
Ki = 0.7233 + 0.7639 = 1.4872 J
Finally the speed:
V = √(2 * 1.4872) / 4.8
V = 0.7872 m/sHope this helps
