Question

for how long should a force of hundred Newton act on a body of mass 20 kg at rest so that it acquires a velocity of 100 M per second

Answer 1

So acceleration of the body can be calculated as:

F = ma

F = 100 N and m = 20 kg

a = 100/20 = 5 m/s2

Since, the force is acting constantly over the body, the acceleration is uniform; the equations of motion can be applied:

v = u + at

Where v = 100 m/sec, a = 5 m/s2 and u = 0 (rest).

t = v/a = 100/5 = 20 sec

Answer 2

$\large\blue{heya mate!!}$

Force = 20 N

Mass = 20 kg

From Newton's second law

Acceleration = Force / Mass

= 20 N / (20 kg)

= 1 m/s²

Now, use equation of motion

v = u + at

Where

v = Velocity after time "t'

u = Velocity when "t = 0"

a = Acceleration of body

t = Time taken for the body to change its velocity from "u" to "v"

t = (v - u)/a

= (100 m/s - 0 m/s) / (1 m/s²)

= 100 s