Elastic and inelastic collisions — NEET & JEE Questions

Question 1 · difficulty L1 · recall

In an isolated collision, which quantity is always conserved?

• A. Linear momentum
• B. Kinetic energy
• C. Speed of each body
• D. Mechanical energy in every form

Question 2 · difficulty L2 · understanding

A perfectly elastic collision is one in which

• A. only momentum is conserved
• B. both momentum and total kinetic energy are conserved
• C. kinetic energy is completely lost
• D. the bodies necessarily stick together

Question 3 · difficulty L2 · understanding

In a perfectly inelastic collision, the colliding bodies

• A. rebound with equal speeds
• B. stick together after collision
• C. conserve kinetic energy
• D. must have equal masses

Question 4 · difficulty L2 · understanding

For a one-dimensional elastic collision between two bodies, the relative speed of separation is

• A. greater than the relative speed of approach
• B. equal to the relative speed of approach
• C. always zero
• D. half the relative speed of approach

Question 5 · difficulty L3 · application

A $2\,\text{kg}$ body moving at $4\,\text{m s}^{-1}$ collides and sticks to a $2\,\text{kg}$ body initially at rest. What is their common speed?

• A. 1 m/s
• B. 2 m/s
• C. 3 m/s
• D. 4 m/s

Question 6 · difficulty L3 · application

A $1\,\text{kg}$ ball moving at $6\,\text{m s}^{-1}$ collides head-on elastically with an identical ball at rest. What happens ideally?

• A. The first stops and the second moves at 6 m/s
• B. Both move at 3 m/s
• C. The first rebounds at 6 m/s and the second stays at rest
• D. Both stop

Question 7 · difficulty L3 · application

A $3\,\text{kg}$ body moving at $5\,\text{m s}^{-1}$ sticks to a $2\,\text{kg}$ body moving in the same direction at $1\,\text{m s}^{-1}$. What is the final speed?

• A. 2.0 m/s
• B. 3.0 m/s
• C. 3.4 m/s
• D. 4.0 m/s

Question 8 · difficulty L3 · application

A $1\,\text{kg}$ body moving at $4\,\text{m s}^{-1}$ sticks to a $1\,\text{kg}$ body initially at rest. How much kinetic energy is lost?

• A. 2 J
• B. 4 J
• C. 6 J
• D. 8 J

Question 9 · difficulty L4 · application

A $1\,\text{kg}$ ball moving at $8\,\text{m s}^{-1}$ collides head-on elastically with a stationary $3\,\text{kg}$ ball. What is the final velocity of the 1 kg ball?

• A. $+8$ m/s
• B. $+4$ m/s
• C. $-4$ m/s
• D. $-8$ m/s

Question 10 · difficulty L4 · application

A $2\,\text{kg}$ body moving at $6\,\text{m s}^{-1}$ collides elastically with a stationary $1\,\text{kg}$ body. What is the speed of the 1 kg body after collision?

• A. 2 m/s
• B. 4 m/s
• C. 8 m/s
• D. 12 m/s