Which of the following types of motion on a frictionless plane surface occurs without any force acting on the body?

Motion in a straight line with increasing speed
Motion in a straight line with decreasing speed
Motion in a straight line while momentum remains constant
Motion in a straight line with changing velocity

Correct answer: Motion in a straight line while momentum remains constant

Solution

With no net force the body has zero acceleration, so its velocity and hence momentum stay constant. Straight-line motion with constant (unchanging) momentum is the only option consistent with no force acting.

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
A block A of mass m1 lies on a rough horizontal surface. It is tied to a light string that goes over a smooth pulley at the table’s edge, and the other end carries a hanging block B of mass m2. If block A is moving along the table and the coefficient of kinetic friction between A and the table is μk, what is the tension in the string?

⚔️ Practice JEE Main Physics free + battle 1v1 →