Question

A car of mass 1500 kg is moving with constant velocity 10 m/s. Calculate the force
required to move this car ?​

Answer 1

Given info : a car of mass 1500 kg is moving with constant velocity 10 m/s.

To find : the force required to move this car is ..

solution : 1st method : according to Newton's 2nd law of motion, force is the rate of change of linear momentum with respect to time.

i.e., force , F = ΔP/Δt

if velocity of a body remains constant. it means change in linear momentum of the body will be zero [ ∵ change in linear momentum = m(v-u) , here v = u = 10 m/s so, m(v - u) = 0 ]

therefore the force, F = 0/Δt = 0  

2nd method : we know force is the product of mass and acceleration. and acceleration is the rate of change of velocity with respect to time.

here velocity remains constant so the acceleration of the body will be zero. hence the force acting on the body is zero.

therefore the force required to move this car is zero.