Kinetic Energy

Q.

The order of temperature required for thermonuclear fusion to take place is:

1. ${10}^{4}K$

2. ${10}^{5}K$

3. ${10}^{6}K$

4. ${10}^{7}K$

Q. in a house individual power of two elements are 100w amd 150w effective power of their series will be

Q.

A body of mass 10 kg is moving with a velocity 20 m $s^{-1}$. If the mass of the body is doubled and its velocity is halved, find:(i) the initial kinetic energy, and (ii) the final kinetic energy.

Q.

A body of mass 50 kg has a momentum of 3000 kg ms^-1. The velocity and the kinetic energy of the body is

1. 60 ms^-1; 1500 J

2. 60 ms^-1; 36000 J

3. 60 ms^-1; 90000 J

4. 15 ms^-1; 36000 J

Q.

A pebble is thrown up. It goes to a height and then comes back on the ground. State the different changes in form of energy during its motion.

Q.

Explain how the law of conservation of momentum can be used to explain (i) recoil of a gun (ii) motion of a rocket.

Q.

Name the three forms of kinetic energy and give one example of each.

Q.

A rifleman, who together with his rifle has a mass of 100 kg, stands on a smooth surface fire 10 shots horizontally. Each bullet has a mass 10 g projected with a velocity of 800 $\frac{m}{s}$. What velocity does rifleman acquire at the end of 10 shots?

1. -0.8 ms^-1

2. 0.6 ms^-1

3. 0.8 ms^-1

4. -0.5 ms^-1

Q.

For the same kinetic energy of a body, what should be the change in its velocity if its mass is increased to four times its original value?

1. Velocity should be halved

2. Velocity should be doubled

3. Velocity should be constant

4. Velocity is independent

Q.

A ball of mass 0.5 kg slows down from a speed of 5ms^-1 to 3ms^-1.Calculate the change in kinetic energy of the ball.

Q.

A stone of mass 64.0 g is thrown vertically upward from the ground with an initial speed of 20.0 ms^-1. The gravitational potential energy at the ground level is considered to be zero. Applying the principle of conservation of energy, the potential energy attained the total energy of the stone at its halfway point can be calculated to be: (g= 10 m s^-2).

1. 12.8 J

2. 12800 J

3. 0.64 J

4. 640 J

Q.

A bomb of mass 9 kg initially at rest explodes into two pieces of masses 3 kg and 6 kg. If the kinetic energy of 3 kg mass is 216 J, then the velocity of 6 kg mass will be

1. 4 ms^-1

2. 3 ms^-1

3. 2 ms^-1

4. 6 ms^-1

Q.

Two particles A and B of equal masses are suspended from two massless springs of spring constants $K_1$ and $K_2$ respectively. If the maximum velocities during oscillations are equal, the ratio of the amplitude of A and B is:

1. $\frac{K_1}{K_2}$

2. $\sqrt{\frac{K_1}{K_2}}$

3. $\sqrt{\frac{K_2}{K_1}}$

4. $\frac{K_2}{K_1}$

Q.

A spring is kept compressed by a small trolley of mass 0.5 kg lying on a smooth horizontal surface as shown in the figure given below:

When the trolley is released, it is found to move at a speed of 2 ms^-1. What potential energy did the spring possess when compressed?

1. 1000 J

2. 0.5 J

3. 2 J

4. 1 J

Q.

Calculate the decrease in the kinetic energy of a moving body if its velocity reduces to half of the initial velocity.

Q.

What do you understand by the kinetic energy of a body?

Q.

If the speed of a car is halved, how does its kinetic energy change?

Q. A bullet of mass $‘m^{\prime }$, moving with a speed $‘v^{\prime }$ strikes a wooden block of mass $M$ kept at rest and gets embedded in it. The speed of this embedded block will be:

1. $\left(\sqrt{\frac{M}{M+m}}\right)v$
2. $\left(\sqrt{\frac{m}{M+m}}\right)v$
3. $\left(\frac{m}{M+m}\right)v$
4. $\left(\frac{m+M}{Mm}\right)v$

Q.

Find the kinetic energy of a body of mass 1 kg moving with a uniform velocity of 10 m $s^{-1}$.

Q.

Calculate the kinetic energy of a body of mass 2 kg moving with a speed of $10m{s}^{-1}.$

1. 150 J

2. 100 J

3. 200 J

4. 0 J

Q.

Give an example where, when a body is released from a height, the potential energy of the body is gradually transformed into kinetic energy?

Q. what is the value of Rydbergs constant-109677/cm or -2.18*10raised to the power-18

Q.

What is the relationship between the kinetic energy and work done?

Q.

Kinetic energy is proportional to the square root of the velocity.

1. True

2. False

Q. A light and a heavy body have equal kinetic energies. The light body has greater momentum.

1. True
2. False

Q. A quarter horse power motor runs at a speed of 600 rpm. Assuming 40% efficiency, the work done by the motor in one rotation will be a)7.46 J b)7400J c)74.6J d)7.46 erg

Q.

While playing a football match, Krish collided and got entangled with Tom who was playing for opposite team and running from opposite side. The mass of Krish was 40 kg and the mass of Tom was 60 kg. If Tom was running with a velocity of 4 m/s and Krish was running with a velocity of 3 m/s, If Krish stops completely, find the velocity of tom after collision assuming other forces were negligible (in m/s).

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Q.

If a ball is thrown upward, what type of energy changes take place?

Q.

Does height affect Momentum ?

Q.

Two bodies of mass 3 kg and 1 kg have equal momentum. Ratio of their kinetic energy is:

1. 1:1

2. 9:1

3. 2:1

4. 1:3