Question

This velocity of a particle decrease uniformly from 20m/s to zero in 10s shown in figure . If the mass of the particle is 2kg, then identify the correct statement
a)the net force acting on the particle is opposite to the direction of the motion
b)the work done by friction force is -400J
c)the magnitude of friction force acting on the particle is4N
d)all of the above

Answer 1

(a) correct
Explanation:
Velocity is decreasing. Hence force is acting in opposite direction.

(b) correct
Explanation:
Work = Change in kinetic energy
= 0.5 m(v² - u²)
= 0.5 × 2 × (0 - 20²)
= -400 J

(c) correct
Explanation:
F = ma
= m (v - u) / t
= 2 kg × (0 - 20 m/s) / 10 s
= -4 N
Magnitude of friction is 4 N

∴ (d) is the correct option.