Question

a force acting on a body of mass 20kg changes its velocity from 20 metre per second to 40 metre per second in 5 second calculate the force​

Answer 1

Answer :

⇒ 80 newton.

Explanation :

Here, we have to find the force which changed the velocity of a body of mass, m = 20 kg from u = 20 m/s to v = 40 m/s in time t = 5 seconds.

We know,

Force is the change in momentum per unit time. It's SI Unit is newton denoted by N.

So, Let us find the change in momentum,

Momentum of a body can be calculated as,

⇒ p = mv

where,

• p is momentum
• m is mass
• v is velocity

So,

⇒ Change in momentum = mv - mu

⇒ ∆p = m(v - u)

⇒ ∆p = 20 × (40 - 20)

⇒ ∆p = 20 × 20

⇒ ∆p = 400 kg ms⁻¹

Hopefully, we are given the change in time which is 5 seconds.

We know,

⇒ Force = Change in momentum / Time

⇒ F = ∆p / ∆t

⇒ F = 400 / 5

⇒ F = 80 newton.

Hence, The force which changed the velocity of the body is calculated as 80 newton.