Conservation of Momentum

Q.

From a rifle of mass $4kg$, a bullet of mass $50g$ is fired with an initial velocity of $35m{s}^{-1}$. Calculate the initial recoil velocity of the rifle.

Q.

A$5000kg$ rocket is set for vertical firing. The exhaust speed is$800m{s}^{-1}$. To give an initial upward acceleration of $20m{s}^{-2}$, the amount of gas ejected per second to supply the needed thrust will be (take, $g=10m{s}^{-2}$ ).

1. $127.5kg{s}^{-1}$

2. $187.5kg{s}^{-1}$

3. $185.5kg{s}^{-1}$

4. $137.5kg{s}^{-1}$

Q. If a bomb at rest explodes and splits into two equal fragments, the fragments will move in

1. one direction and with equal velocities.
2. opposite directions with different velocities.
3. opposite directions with equal velocities.
4. one direction with different velocities.

Q. Which of the following quantities remain conserved in any collision?

1. Kinetic energy of the system
2. Total energy of the system
3. Momentum of the system
4. Potential energy of the system

Q.

On the earth, a stone is thrown from a height in a direction parallel to the earth’s surface while another stone is simultaneously dropped from the same height. Which stone would reach the ground first and why?

Q.

Explain why it is easier to stop a tennis ball in comparison to a cricket ball moving with the same speed?

Q.

Mass of a body is tripled and its velocity is halved. Its momentum will

1. Double

2. Triple

3. Become 3/2 times the original

4. Become 2/3 times the original

5. Remains constant

Q.

Two identical bullets are fired one by a light rifle and another by a heavy rifle with the same force. Which rifle will hurt the shoulder more and why?

Q.

A rocket of mass $1000kg$ is exhaust gases at a rate of $4{kgs}^{-1}$ with a velocity of $3000m{s}^{-1}$. The thrust developed on the rocket is

1. $12000N$

2. $120N$

3. $800N$

4. $200N$

Q.

A bullet of mass $20g$ travelling horizontally with a velocity of $100m/s$ strikes a wooden block and comes to rest in $0.05s$. Calculate the magnitude of force N exerted by the wooden block on the bullet.

Q. Rocket works on the principle of conservation of linear momentum.

1. True
2. False

Q. What is the momentum of a man of mass $100\text{kg}$ when he walks with a uniform velocity of $2{\text{m s}}^{-1}$?

1. $300{\text{kg m s}}^{-1}$
2. $50{\text{kg m s}}^{-1}$
3. $100{\text{kg m s}}^{-1}$
4. $200{\text{kg m s}}^{-1}$

Q. The recoil velocity of a gun of $5kg$, if a bullet of $25g$ acquires a velocity of $500m{s}^{-1}$ after firing from the gun, is .

1. $5m{s}^{-1}$
2. $2.5m{s}^{-1}$
3. $2m{s}^{-1}$

Q.

A woman draws water from a well using a fixed pulley. The mass of the bucket and water together is $6.0\mathrm{kg}$. The force applied by the woman is $70\mathrm{N}$. Calculate the mechanical advantage. (Take $g=10\mathrm{m}/{\mathrm{s}}^2$ )

Q. A $6kg$ mass moving with a velocity of $20m{s}^{-1}$ collides with another $2kg$ mass moving in opposite direction with a velocity of $10m{s}^{-1}$. The momentum of system is.

1. $140kgm{s}^{-1}$
2. $50kgm{s}^{-1}$
3. $100kgm{s}^{-1}$

Q.

A thin girl & a fat man have same KE. If the ratio of their masses is 4:25, calculate the ratio of their momentum.

1. 2:5

2. 5:2

3. 4:25

4. 25:4

Q.

A thin girl & a fat man have same KE. Which of the 2 have a greater momentum? If the ratio of their masses is 4:25, calculate the ratio of their momentum.

1. 1:5

2. 2:5

3. 3:5

4. 4:5

Q. A rocket works on the principle of

1. conservation of mass
2. conservation of energy
3. conservation of liner momentum
4. none of these

Q.

A car of mass $1200kg$ moving at a speed of $72km{h}^{-1}$collides with another car of mass $1500kg$which is at rest. What is the common velocity of the two
cars, if they move together after the collision (m s–1)?

1. $32.04$

2. $3.204$

3. $8.9$

4. $89$

Q. Assertion :A rocket works on the principle of conservation of linear momentum. Reason: Whenever there is the change in momentum of one body, the same change occurs in the momentum of the second body of the same system but in the opposite direction.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q.

In the diagram below the red arrows represent

1. Tension T acting vertically upward, applied by the string on the ball and Gravitational pull (mg) acting on the ball acting vertically downward

2. Reaction of the tensions represented by the blue arrows

3. The Weights of the string and the ball

4. Tension T applied by the string on the ball acting vertically downward and Gravitational pull (mg) acting vertically upward

Q.

A women draws water from a well using a fixed pulley. The mass of the bucket and water together is $6kg$. The force applied by the women is $70N$. The mechanical advantage is

1. $0.96$

2. $0.86$

3. $0.76$

4. $0.66$

Q.

If the initial velocity of m₁ is v m/s and initial velocity of m₂ is 2 v m/s. After collision m₂ stops, then what is the final velocity of m₁ after collision? If m₁ = m Kg and m₂ = 2m Kg.

1. 10 v m/s

2. 2 v m/s

3. 5 v m/s

4. 0

Q.

Rocket works on the principle of conservation of

1. Mass

2. Energy

3. Momentum

4. Velocity

Q. Why is it easier to catch a tennis ball as compared to cricket ball moving with the same velocity ?

Q. A rocket of mass $1000kg$ is exhaust gases at a rate of $4kg/s$ with a velocity $3000m/s$. The thrust developed on the rocket is

1. $12000N$
2. $800N$
3. $200N$
4. $120N$

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

Q. A 6000 Kg rocket is set for vertical fring if the exhaust speed is $1000m{s}^1$ The amount of gas that must be ejected per second to supply the thrust needed to overcome the weight of the rocket is $(g=10m{s}^2)$

1. 30 Kg/s
2. 60 Kg/s
3. 75 Kg/s
4. 90 Kg/s

Q. A 6000 kg rocket is set for vertical firing. If the exhaust speed is 1000 m/sec. How much gas must be ejected each second to supply the thrust needed to overcome the weight of rocket.

1. $60kg/sec$
2. $6kg/sec$
3. $600kg/sec$
4. $6000kg/sec$

Q.

The quantity of motion contained in a body is 50 kg m/s. If the body moves with a speed of 5 m/s, what is the mass of the body?