Question

A constant force acting on a body of mass 3.0kg changes its speed from 2.0ms^-1 to 3.5 ms^-1 in 25s. The direction of motion of the body remains unchanged. What is the magnitude and direction of the force?

Answer 1

m = 3kg; u = 2ms^-1; v = 3.5 ms^-1;

t = 25s ; F = ?

v = u + at

3.5 = 2 + 25a or a = 0.06 ms^-2

F = ma = 3kg × 0.06 ms^-2 = 0.18N.

The direction of force is along the direction of motion.