Momentum Conservation Quiz

Which of the following correctly describes the principle of conservation of momentum?

• Momentum is the product of mass and velocity.

• Momentum is conserved only in elastic collisions.

• Momentum is conserved by all bodies in a collision.

• Momentum is conserved providing no external force act.

A particle of mass m and velocity u is made to collide head-on with a stationary particle of mass M. Given that the collision is elastic, what is the velocity of the particle of mass M after the collision?

• u

• mu/M

• (2mu)/(M+m)

• (M−m)u/(M+m)

In a collision between two steel balls suspended on strings, what are quantities that must be conserved?

• kinetic energy, total energy and momentum

• kinetic energy and momentum only

• kinetic energy and total energy only

• total energy and momentum only

Two spheres, each of mass m, move with speed v towards each other and have a head-on elastic collision. Which one of the following statements is correct?

• The spheres stick together on impact.

• The total kinetic energy after impact is mv^2.

• The total kinetic energy before impact is zero.

• The total momentum before impact is 2mv.

A body, initially at rest, explodes and breaks into two masses. The masses, M1 and M2, move apart with speeds v1 and v2 respectively. What is the ratio v1/v2?

• M1/M2

• M2/M1

• (M1/M2)^(1/2)

• (M2/M1)^(1/2)

What is the change of energy while operating a light bulb?

• chemical→heat

• electrical energy→heat & light

• heat & light→electrical energy

• electrical energy→kinetic energy

What are the main energy changes in a battery-operated remote control car?

• chemical→electrical→kinetic

• chemical→wave→kinetic

• wave→electrical→kinetic

• electrical→chemical→wave

A battery supplies 500 J of electrical energy to a motor such that an object moves horizontally for 40 m under the influence of a 6 N pulling force. What is the efficiency of the motor?

• 21%

• 24%

• 48%

• 75%

A particle is displaced from position r1= (3i+2j−6k) to another position r2= (14i+13j+9k) under the impact of a force 5i Newton. The work done will be given by

• 55J

• 65 J

• 45 J

• 75 J

A force F acting on an object varies with distance x as shown in the below figure. The force is in N and x in m. The work done by the force in moving the object from x=0 to x=6 m is

• 18 J

• 13.5 J

• 9 J

• 4.5 J