Question

Under the action of a constant retarding force, the speed of a particle of mass 1kg reduces from 72kmph to 0 in 10 seconds . The force(in N) acting on the particle is ??

Answer 1

mass= 1kg

initial speed=72kmph

final speed=0

RETARDATION = (72-0)÷10

=7.2

so force = mass ×retardation

=1kg × 7.2×5/18

=2N

Answer 2

Answer:

Force, F = -2 N

Explanation:

It is given that,

Mass of the particle, m = 1 kg

Initial speed of the particle, u = 72 km/h = 20 m/s

Final speed of the particle, v = 0

Time taken, t = 10 s

Let F is the force acting on the particle. It can be calculated using the second law of motion as :

F = ma

$F=\dfrac{m(v-u)}{t}$

$F=\dfrac{1\times (0-20)}{10}$

F = -2 N

So, the force acting on the particle is 2 N and it is acting in opposite direction.