Physics Questions - Laws of Motion and Energy

The forces involved in Newton’s third law act ____

• On the same object

• On different objects

• In same direction

• On five bodies

Answer explanation

The forces involved in Newton’s third law act on different objects.

Two bodies in contact experience forces in ________

• Same direction

• Opposite directions

• Perpendicular directions

• Five different directions

Answer explanation

Two bodies in contact experience forces in opposite directions.

A man hits a ball with a force of 5 N. What force does the man experience?

Answer explanation

The man experiences a force equal in magnitude but opposite in direction, so he experiences a force of -5 N.

A driver hits a light pole with a force a 100 N. What force does the car experience?

Answer explanation

The car experiences an equal and opposite force of 100 N according to Newton's third law of motion.

A truck with a mass of 2500 Kg travelling with an acceleration of 5 m/s^2 hits a large stone. What force does the truck experience?

Answer explanation

The force experienced by the truck can be calculated using the formula: Force = mass x acceleration. Substituting the values, Force = 2500 Kg x 5 m/s^2 = 12500 N.

A man and a kid accidentally hit each other. What is true about the forces experienced by them?

Answer explanation

The forces experienced by the man and the kid are equal in magnitude but opposite in direction, according to Newton's third law of motion.

A man is standing still. The force by the man on the earth is F1. The force by the earth on the man is F2. Which one of the following is true?

• F1=F2

• F1=−F2

• F1=5(F2)

• 2(F1)=F2

Answer explanation

The correct choice is F1=F2 because according to Newton's third law of motion, the force exerted by the man on the earth is equal in magnitude and opposite in direction to the force exerted by the earth on the man.

Two bodies moving with constant velocities collide with each other. Which of the following quantities remain conserved?

• Momentum

• Speed

• Force

• Velocity

Answer explanation

Momentum remains conserved when two bodies moving with constant velocities collide. Speed, force, and velocity are not conserved in this scenario.

A ball is moving with a constant velocity. After some time, it collides with a wall. Which one of the following remains conserved except momentum?

• Energy

• Displacement

• Power

• Force

Answer explanation

Energy remains conserved except momentum in the collision of a ball with a wall.

A variable mass body with an initial mass of 5 kg is moving with a velocity of 5 m/s initially, after some time the velocity increases to 10 m/s, what is the new mass if the body is moving in the absence of any external force?

Answer explanation

The mass remains constant in the absence of external force, so the new mass is still 5 kg.