Answer:
The sound travels differently in different medium according the density of the medium.
Explanation:
The sound travels faster in dense medium and can be heard by the vibration of the bone present in the ear. The ear plugs reduce the sound intensity in both medium water and on land (air).
In air the sound is not heard properly due to the earplugs that stops the as the vibration are not able to produce as sound is not able to reach to middle ear, but Navy researchers have discovered that sound under water is heard by the bone present behind the ear, vibrations mastoid.
If you have a 200g sample of a radioactive isotope that has a half life of 50 years, hc
much will you have left at the end of 200 years?
a. 12.5 g
b. 100 g
c. 50 g
d. 25 g
Answer:
The correct option is;
a. 12.5 g
Explanation:
The given parameters are;
The initial mass of the radioactive substance = 200 g
The half life of the radioactive substance = 50 years
The time duration for the disintegration = 200 years
The formula for half life is given as follows;
[tex]N(t) = N_0 \left (\dfrac{1}{2} \right )^{\dfrac{t}{t_{1/2}}[/tex]
Where:
N(t) = Quantity of the remaining substance
N₀ = Initial radioactive substance quantity = 200 g
t = Time duration = 200 years
[tex]t_{1/2}[/tex] = Half life of the radioactive substance 50 years
Therefore, we have;
[tex]N(t) =200 \times \left (\dfrac{1}{2} \right )^{\dfrac{200}{50} } =200 \times \left (\dfrac{1}{2} \right )^4 = 12.5 \ g[/tex]
Therefore, at the end of 200 years, the quantity left = 12.5 g.
What two factors determine how much potential energy an object has?
Answer:
The mass of the object and its height in the gravitational field of the Earth.
Explanation:
If we are talking about gravitational potential energy which is defined as:
[tex]U=m\,*\,g\,*\,h[/tex]
being "m" the object's mass, "g" the acceleration due to gravity, and "h" the height at which the object is located relative to the conventionally picked level for zero of potential energy.
As long as the value of "g" is constant, the only two variables that determine the gravitational potential energy are the mass (m) of the object and its relative height (h).
Answer:
The objects weight and height above Earth's surface
Explanation:
K12 :)
use the techniques to find the unit for speed
Answer:
The formula for speed is speed=distance
time
Explanation:
to work out what the units are for speed,you need to know the units for distance and time.In this example,distance is in metres(m) and time is in seconds (s) , so the units for speed is metre per second (m/s).
Astronomers were at first surprised to find complicated molecules in the interstellar medium. They thought ultra-violet light from stars would break apart such molecules. What protects the molecules we observe from being broken apart
Answer:
The dust present in the clouds.
Explanation:
The complicated composition molecules that can be found in space are generally associated with clouds of dust. The significant amount of dust in these clouds provides protection not only for these molecules, but for any body that makes up or is associated with dust clouds.
It is exactly this dust that protects the molecules against the action of ultraviolet rays.
calculate the force exerted by a mental ball having a mass of 70kg moving with speed of 20m/s>2
Answer:
F = 1400 N
Explanation:
It is given that,
Mass of the ball, m = 70 kg
It is moving with an acceleration of 20 m/s². We need to find the force exerted by the ball.
Force is given by the product of mass and acceleration. So,
F = ma
[tex]F=70\ kg\times \ 20m/s^2\\\\F=1400\ N[/tex]
So, the force of 1400 N is exerted by a metal ball.
a.
more iOCUS
8.
A force of 8N is applied to the body to cover 50 cm distance. How much work is done
by this fore?
400J
b. 40J
d. 40kg
a.
C.
Answer:
[tex] \boxed{\sf Work \ done = 4 \ J} [/tex]
Given:
Force = 8 N
Distance covered by the body = 50 cm = 0.5 m
Explanation:
Work Done = Force × Distance covered by the body
= 8 × 0.5
= 4 J
Two 110 kg bumper cars are moving toward each other in opposite directions. Car A is moving at 8 m/s and Car Z at −10 m/s when they collide head–on. If the resulting velocity of Car A after the collision is −10 m/s, what is the velocity of Car Z after the collision? 10 m/s −8 m/s 8 m/s 10 m/s-
Answer:
it will be 8ms-1
Explanation:
MaUa+MbUb=MaVa+MbVb
A body of mass 20 kh changes its velocity from 5m/s to 17 m/s in 3 seconds. find the force applied on this body .
please answer fast
Answer:
80 N.
Explanation:
The following data were obtained from the question:
Mass (m) = 20 Kg
Initial velocity (u) = 5 m/s
Final velocity (v) = 17 m/s
Time (t) = 3 secs
Force (F) =.?
Next, we shall determine the acceleration of the body.
Acceleration is simply defined as the rate of change of velocity with time. Mathematically, it is expressed as:
Acceleration = change of velocity /time
Acceleration (a) = (final velocity (v) – initial velocity (u)) / time (t)
a = (v – u) /t
With the above formula, we can obtain the acceleration of the body as follow:
Initial velocity (u) = 5 m/s
Final velocity (v) = 17 m/s
Time (t) = 3 secs
Acceleration (a) =?
a = (v – u) /t
a = (17 – 5) /3
a = 12/3
a = 4 m/s²
Finally, we shall determine the force applied to the body as follow:
Force (F) = mass (m) x acceleration (a)
F = ma
Mass (m) = 20 Kg
Acceleration (a) = 4 m/s²
Force (F) =.?
F = ma
F = 20 x 4
F = 80 M.
Therefore, the force applied on the body is 80 N.
Calculate the intensity of current flowing through a computer that consumes 180W and operates at 120 V.
A.)0,66 A
B.)12600 A
C.)1,5 A
D.)60 A
Answer:
C) 1.5 A
Explanation:
P = IV
180 W = I (120 V)
I = 1.5 A
A train is moving along a horizontal track. A pendulum suspended from the roof makes an angle of 4° with the vertical. If g=10m/s2, what is the acceleration of the train?
Answer:
Train accaleration = 0.70 m/s^2
Explanation:
We have a pendulum (presumably simple in nature) in an accelerating train. As the train accelerates, the pendulum is going move in the opposite direction due to inertia. The force which causes this movement has the same accaleration as that of the train. This is the basis for the problem.
Start by setting up a free body diagram of all the forces in play: The gravitational force on the pendulum (mg), the force caused by the pendulum's inertial resistance to the train(F_i), and the resulting force of tension caused by the other two forces (F_r).
Next, set up your sum of forces equations/relationships. Note that the sum of vertical forces (y-direction) balance out and equal 0. While the horizontal forces add up to the total mass of the pendulum times it's accaleration; which, again, equals the train's accaleration.
After doing this, I would isolate the resulting force in the sum of vertical forces, substitute it into the horizontal force equation, and solve for the acceleration. The problem should reduce to show that the acceleration is proportional to the gravity times the tangent of the angle it makes.
I've attached my work, comment with any questions.
Side note: If you take this end result and solve for the angle, you'll see that no matter how fast the train accelerates, the pendulum will never reach a full 90°!
A storm is moving east towards your house at an average speed of 35 km / hr. If the storm is currently 80 km from your house, how much time do you expect it to arrive
Answer:
The expected time is 2.28 hours.
Explanation:
The speed of storm = 35 km/hr
The distance between the house and the storm = 80 km.
Now, we have to find the time taken by storm to arrive at the house. Here, we can determine the time by dividing the distance with speed.
The time, taken by storm = Distance/speed
The time, taken by storm = 80 / 35
The time, taken by storm = 2.28 hours.
While driving on a highway, your HMMWV starts to pull to one side. You stop and check your tires – one tire is going flat. There is no spare, but the affected tire has a runflat device installed, and you are only 5 miles from the motor pool. What is your maximum allowable speed when driving with one flat tire?
Answer:
30 miles people hour (mph)
Explanation:
The maximum speed for one flat tyre is 30mph, for both tyres it is 20 mph and for two tyres on the same side it is 30mph. When a tyre is punctured driving at high speed should be avoided and not too long distance should be covered to avoid further accident and for the safety of other vehicles. Speed limit and distance for flat tires should be strictly followed.
The distance covered by a body along the x axis is given by x=2t^3+5t^2+t where t is measured in seconds and x is in meter. Find average speed in a time interval from t= 0s and t=2s
Explanation:
It is given that,
The distance covered by a body along the x-axis is given by :
[tex]x=2t^3+5t^2+t[/tex]
t is in seconds and x is meters
Speed of the body is given by :
[tex]v=\dfrac{dx}{dt}\\\\v=\dfrac{d(2t^3+5t^2+t)}{dt}\\\\v=6t^2+10t+1[/tex]
At t = 0,
[tex]v=6(0)^2+10(0)+1=1\ m/s[/tex]
At t = 2 s,
[tex]v=6(2)^2+10(2)+1=45\ m/s[/tex]
So, the average speed in a time interval from t= 0s and t=2s is 45 m/s.
if you ran 15 km/hr for 2.5 hours, how much distance would you cover?
Answer: 37.5 km
Explanation:
The question is that
If you ran 15 km/hr for 2.5 hours, how much distance would you cover ?
Where
Speed = 15 km/ hr
Time = 2.5 hours
Using the formula for speed.
Speed = distance/time
Substitute speed and time into the formula
15 = distance/ 2.5
Make distance the subject of formula by cross multiplying.
Distance = 15 × 2.5
Distance = 37.5 km.
If 5 complete oscillations of a sound wave pass through a point in 0.5 s and the speed of sound was recorded to be 10 m/s, then find the wavelength of the sound.
Answer:
λ = 2.5m
Explanation:
Given the following :
Speed of sound (v) = 10m/s
If 5 oscillations pass through a point in 0.5seconds;
Time taken (period) for 1 oscillation is :
Number of oscillations / total time taken
5 / 0.5 = 0.25 seconds
Wavelength, period and Velocity are related by the formula:
v = λ / T
λ = v * T
λ = 10 * 0.25
λ = 2.5 m
A student is planning an investigation on the properties of different types of matter. What would be the best method to find the volume of an irregularly shaped object, such as a rock?
Explanation:
Volume is the amount of space an object takes up, while mass is the amount of matter in an object. ... To find the volume of an irregular sized object, one would use the displacement method for measuring volume and place the object in water and measure the amount of water that is displaced.
Answer:
To measure the volume of an irregularly shaped object, pour some water in a measuring cylinder. Then suspend the irregularly shaped object with a thread. After that , move the object gradually downwards and immerse it in water. The volume of the irregularly shaped object is the difference between the volume of the liquid before and after. After measuring the difference, we come to know about the volume of the irregularly shaped object.
I need help. can I get some
Explanation:
a) Acceleration is the slope of the velocity vs time graph. When velocity vs time is a straight line, that means the acceleration is a constant. F = ma, so the resultant force is also constant.
b) As air resistance increases, the acceleration begins to decrease.
c) A falling object stops accelerating when it reaches terminal velocity.
d) F = ma, so when the acceleration is 0, the resultant force is also 0.
the value of g is more in the poles of the earth,why?
Answer:
Explanation:
beacuse the poles are the cause of graIt's due to the rotation of earth about its own axis. Due to the rotation, objects placed on the surface of earth also rotates . Their rotational kinetic energy prevents them from the free fall along gravitational pull. This phenomena can also be explained sitting on the earth surface as their free fall suffers a centrifugal barrier due to the rotation. In this explanation, the term, centrifugal barrier, appears because earth is a non-inertial frame. Centrifugal force in a non intertial frame acts opposite to gravitational force.
The rotational energy / centrifugal barrier on a object depends on the radius of the circle linearly ; the circle is drawn around the axis of rotation from the point where the object placed. Now you can imagine that its radius get shorter and shorter towards the pole from the equator. Hence the barrier decreases if we move from equator to the both poles of earth. Hence garvitational force on a object i.e. its weight, so the g, becomes effectively maximum on the poles and minimum on the equator.
Because the neutron has no charge, its mass must be found in some way other than by using a mass spectrometer. When a neutron and a proton meet (assume both to be almost stationary), they combine and form a deuteron, emitting a gamma ray whose energy is 2.2233 MeV. The masses of the proton and the deuteron are 1.007 276 467 u and 2.013 553 212 u, respectively. Based on this data, what is the mass of the neutron
Answer:
Explanation:
Energy of gamma ray = 2.2233 MeV
Let mass of neutron be n amu
mass defect of deuteron = 2.013553212 - ( 1.007 276 467 + n ) u .
in terms of energy this mass defect will be equal to energy of gamma ray
1 amu = 931 MeV
931 [ 2.013553212 - ( 1.007 276 467 + n ) ] = 2.2233
( 1.007 276 467 + n ) - 2.013553212 = .00238807733
n = 1.008664822 amu
so mass of neutron = 1.008664822 amu
20 pts. What type of forces do not change the motion of an object? Acceleration forces Balanced forces Inertia forces Unbalanced forces
Answer:
Balanced forces
Explanation:
Answer:
its balance force
Explanation:
how much electrical energy is used by the river cooker oven rated 800 W ,230 V is switched on for 30 minutes
Answer:
E = 1440 kJ
Explanation:
It is given that,
Power of a cooker oven is 800 W
Voltage at which it is operated is 230 V
Time, t = 30 minutes = 1800 seconds
We need to find the electrical energy used by the cooker oven. The product of power and time is equal to the energy consumed. So,
[tex]E=P\times t\\\\E=800\ W\times 1800\ s\\\\E=1440000\ J\\\\\text{or}\\\\E=1440\ kJ[/tex]
So, electrical energy of 1440 kJ is consumed by the cooker oven.
Match words at the left to the correct blanks in the sentences on the right. Not all words will be used.1. The energy that drives the expansion of a star into a subgiant or red giant comes from HYDROGEN SHELL FUSION2. Stars with mass greater than about 8 solar masses are considered HIGH-MASS STARS3. The final stage of core fusion in a low-mass star is HELIUM FUSION4. Stars that are fusing hydrogen in their cores are MAIN-SEQUENCE STARS5. When it dies, a high-mass star explodes as a SUPERNOVA6. A star that is expanding (into a subgiant and then a giant) has a(n) INERT HELIUM CORE7. When it dies, a low-mass star expels a PLANETARY NEBULA8. Stars with masses less than about two solar masses are considered LOW-MASS STARS
Answer:
In what way is iron unique among the elements?
It has the lowest mass per nuclear particle.
Match words at the left to the correct blanks in the sentences on the right. Not all words will be used.
-The energy that drives the expansion of a star into a subgiant or red giant comes from HYDROGEN SHELL FUSION
-Stars with mass greater than about 8 solar masses are considered HIGH-MASS STARS
-The final stage of core fusion in a low-mass star is HELIUM FUSION
-Stars that are fusing hydrogen in their cores are MAIN-SEQUENCE STARS
-When it dies, a high-mass star explodes as a SUPERNOVA
-A star that is expanding (into a subgiant and then a giant) has a(n) INERT HELIUM CORE
-When it dies, a low-mass star expels a PLANETARY NEBULA
-Stars with masses less than about two solar masses are considered LOW-MASS STARS
You have a reservoir held at a constant temperature of –30°C. You add 400 J of heat to the reservoir. If you have another reservoir at 0°C, how much heat must you add to it so that both reservoirs have the same increase in entropy?
Answer:
449.38 J
Explanation:
ΔS = ΔQ/T
Where ΔS = entropy change
Q = quantity of heat
T = temperature
First reservoir :
T = –30°C = - 30 + 273 = 243K
Q = 400 J
Second reservoir :
T = 0°C = 273K
Q =?
To have same increase in entropy for both reservoirs :
Q/T of first reservoir = Q/T of second reservoir
400/243 = Q/273
243 * Q = 400 * 273
Q = (400 * 273) / 243
Q = 109,200 / 243
Q = 449.38271
Q = 449.38 J
A 50.5-turn circular coil of radius 4.75 cm can be oriented in any direction in a uniform magnetic field having a magnitude of 0.455 T. If the coil carries a current of 22.5 mA, find the magnitude of the maximum possible torque exerted on the coil.
Answer:
The maximum torque, τ = 3.67 × 10⁻³ Nm
Explanation:
The torque τ = NiABsinθ where N = number of turns of circular coil = 50.5, i = current in circular coil = 22.5 mA = 0.0225 A, A = area of circular coil = πr² where r = radius of circular coil = 4.75 cm = 0.0475 m, B = magnetic field strength = 0.455 T and θ = 90° for maximum torque.
So, τ = NiABsinθ
τ = Niπr²Bsinθ
τ = 50.5 × 0.0225 A × π × (0.0475 m)² × 0.455 T × sin90°
τ = 0.003665 Nm
τ = 3.665 × 10⁻³ Nm
τ ≅ 3.67 × 10⁻³ Nm
So the maximum torque, τ = 3.67 × 10⁻³ Nm
In 1869, Dmitri Mendeleev was trying to arrange the 65 known elements in a logical way. He arrived at the solution when he saw the elements arranged by atomic weight in a dream. He tried this arrangement and it worked! What is this an example of?
Answer:
Creative thinking
Explanation:
As you can see in the question above, when Mandleev needed to organize the chemical elements in a logical, organized and efficient way, he thought until he came to the conclusion of organizing them according to the atomic weight of each one. This is a clear example of creative thinking, which is the term that refers to the act of solving a problem based on thought and reasoning.
Answer:
Creative thinking
Explanation:
"For a first order instrument with a sensitivity of .4 mV/K and a time" constant of 25 ms, find the instrument’s response as a function of time for a sudden temperature increase from 273 K to 473 K. Before the temperature increase, the instrument output was a steady 109.2 mV. Plot the response y(t) as a function of time. What are the units for y(t)? Find the 90% rise time for y(t90) and the error fraction, Γ(t90).
Answer:
Explanation:
Given that:
For a first order instrument with a sensitivity of .4 mV/K
constant c = 25 ms = 25 × 10⁻³ s
The initial temperature [tex]T_1[/tex] = 273 K
The final temperature [tex]T_2[/tex] = 473 K
The initial volume = 0.4 mV/K × 273 K = 109.2 V
The final volume = 0.4 mV/K × 473 K = 189.2 V
the instrument’s response as a function of time for a sudden temperature increase can be computed as follows:
Let consider y to be the function of time i.e y(t).
So;
y(t) = 109.2 + (189.2 - 109.2)( 1 - [tex]\mathbf{e^{-t/c}}[/tex])mV
y(t) = (109.2 + 80 ( 1 - [tex]\mathbf{e^{t/25\times 10^{-3}}}[/tex])) mV
Plot the response y(t) as a function of time.
The plot of y(t) as a function of time can be seen in the diagram attached below.
What are the units for y(t)?
The unit for y(t) is mV.
Find the 90% rise time for y(t90) and the error fraction,
The 90% rise time for y(t90) is as follows:
Initially 90% of 189.2 mV = 0.9 × 189.2 mV
= 170.28 mV
170.28 mV = (109.2 + 80 ( 1 - [tex]\mathbf{e^{t/25\times 10^{-3}}}[/tex])) mV
170.28 mV - 109.2 mV = 80 ( 1 - [tex]\mathbf{e^{t/25\times 10^{-3}}}[/tex])) mV
61.08 mV = 80 ( 1 - [tex]\mathbf{e^{t/25\times 10^{-3}}}[/tex])) mV
0.7635 mV = ( 1 - [tex]\mathbf{e^{t/25\times 10^{-3}}}[/tex])) mV
t = 1.44 × 25 × 10⁻³ s
t = 0.036 s
t = 36 ms
The error fraction = [tex]\dfrac{189.2-170.28 }{189.2}[/tex]
The error fraction = 0.1
The error fraction = 10%
The acceleration due to gravity near Earth ... Select one: a. varies inversely with the distance from the center of Earth. by. varies inversely with the square of the distance from the center of Earth. c. is a constant that is independent of altitude d. varies directly with the distance from the center of Earth.
Answer:
b. varies inversely with the square of the distance from the center of Earth.
Explanation:
Comparing the Newton's law of universal gravitation and second law of motion;
from Newton's second law of motion,
F = ma ............. 1
from New ton's law of universal gravitation,
F = [tex]\frac{GMm}{r^{2} }[/tex] ........... 2
Equating 1 and 2, we have;
mg = [tex]\frac{GMm}{r^{2} }[/tex]
g = [tex]\frac{GM}{r^{2} }[/tex]
Therefore, the acceleration due to gravity near Earth, g, is inversely proportional to the square of the distance from the center of Earth.
What is the value of work done on an object when a 0.1x102–newton force moves it 30 meters and the angle between the force and the displacement is 25°?
Answer: A. 2.7 x 10^2 joules
Explanation: I’m sorry for the guy above me!
3. What two characteristics do you need to include when defining a force? (a) speed and direction (b) strength and direction (c) acceleration and time (d) distance and direction
4. When a bug traveling west hits the windshield of a car that is traveling east, what can be said about the collision? (a) The bug feels a stronger force than the car. (b) The car and the bug feel the same size force. (c) The car accelerates more than the bug. (d) The bug does not accelerate due to the force.
5. What is the reaction force to the force on a baseball from a bat? (a) The force of the bat on the ball (b) The force of the ball on the ground (c) The force of the bat on the players hand (d) The force of gravity on the
Answer:
2
yes
Explanation:
been submitted to the Theme 20 participants will be there was a lot of fun and I will be there at Home
A baseball weights 1429 (0.142kg) were striked with force of 120N. Calculate its acceleration at
that time. Include the correct unit with your answer. Include one decimal place.
Answer:
a=845.07 m/s2
Explanation:
m=0.142kg
F=120N
a=?
F=m*a /:m
a=F/m
a=120N/0.142kg
a=845,07m/s2
Answer:
a = 845.07 m/s²
Explanation:
As we know ,
as per newton's 2nd law:-
F = ma
therefore
a = F/m
given:
a = ?
F = 120N
m = 0.142 kg
procedure:-
a = 120/0.142
therefore :
a = 845.07 m/s²
