Question

A force acting on a particle of mass 200g. The velocity of particle changes from 15m/'s to 25m/sec in 2s.find it's magnitude

Answer 1

Final Answer : 1N

Steps and Understanding :
1) By Newtons Second Law of Motion,
Force is rate of change of Momentum,
Here, assuming Force is constant.
Mass of particle, m = 200g = 0.2Kg
Final Velocity, v = 25m/s
Initial Velocity, u = 15m/s
Time taken, t = 2s
Then,
F = m(v-u) /t
= 0.2 (25-15)/2.5
=1N

Magnitude of Force is 1N .

Answer 2

Answer: Given u = 15 m/s and v = 25 m/s, mass = 200g=0.2 kg and time t = 2.5 s.

We have v = u + at

a = (v - u)/t

a = (25 - 15)/2.5

a = 10/2.5 = 100/25 = 4 m/s2  

Therefor F = ma = 0.2 x 4 =0.8 N