Question

A constant force acts on body of mass 0.9 kg at rest for 10 s, if the body moves a distance of 250 m the magnitude of force is

(A)4.5 N (B)9.0 N (C)13.5 N (D)18 N

Answer 1

here d= 250m
t= 10 seconds
initial velocity(u)= 0
using equation d= ut +1/2 at2, we will get
250 = 50 xa
a=5m/s2
force= mass x acceleration = 0.9ks x 5m/s2 = 4.5 newton
therefore answer is (a) 4.5 newton

Answer 2

S = u t + 1/2 a t²
250 = 0 + 1/2 * a * 10²

a  = 5 m/sec²

force = mass * acceleration = 0.9 kg * 5 m/sec² = 4.5 Newtons