Exams › JEE Main › Physics

A 0.15 kg ball strikes a wall at 12 m/s and rebounds with the same speed. If the average force exerted by the wall on the ball during contact is 100 N, how long is the ball in contact with the wall?

1. (1) 0.018 s
2. (2) 0.036 s
3. (3) 0.009 s
4. (4) 0.072 s

Correct answer: (2) 0.036 s

Solution

The momentum change is 2mv because the ball reverses; dividing by the force gives the contact time.

Related JEE Main Physics questions

• Which of the following has the same SI unit as impulse?
• A monkey slides downward from a tree branch with uniform acceleration. If the maximum tension the branch can withstand is 75% of the monkey’s weight, what is the least downward acceleration that will allow the monkey to descend without snapping the branch?
• A 1000 kg car is travelling at 30 m/s. The brakes are applied until it stops. If the friction force between the tyres and the road is 5000 N, how long will the car take to come to rest?
• A rocket initially ejects gas from its rear at a mass rate of 0.1 kg s⁻¹. If the exhaust speed relative to the rocket is 50 m s⁻¹ and the rocket’s mass is 2 kg, what is its acceleration in m s⁻²?
• A block of mass M rests on a rough level floor with coefficient of friction μ. A person applies a horizontal pull, but the block remains at rest. If the total contact force exerted by the floor on the block is F, then
• Which of the following types of motion on a frictionless plane surface occurs without any force acting on the body?

⚔️ Practice JEE Main Physics free + battle 1v1 →