Question

a force acting on a body of mass 20kg changes its velocity from 20m/s to 40m/s in 5 seconds. Calculate the force​

Answer 1

Answer:

for this,

first we have to find its acceleration.,

so, v-u/t=a

then, 40-20/5=4m/s^2

and force =mass ×accleration

mass =20kg

20×4=80N

Answer 2

Given :

• Mass of body, m = 20 kg
• Initial velocity of body, u = 20 m/s
• Final velocity of body, v = 40 m/s
• Time taken for change in velocity, t = 5 s

To find :

• Force on the body, F =?

Formula required :

• First equation of motion

       v = u  +a t

• Expression of Newton's second law of motion

       F = m a

[ Where v is final velocity, u is initial velocity, a is acceleration, t is the time taken, F is force and m is mass of body ]

Solution :

Calculating acceleration of body

Using first equation of motion

→ v = u + a t

→ 40 = 20 + a ( 5 )

→ 40 - 20 = 5 a

→ 20 = 5 a

→ a = 20 / 5

→ a = 4 m/s²

   

Calculating force acting on the body

Using Expression for Newton's second law

→ F = ma

→ F = ( 20 ) ( 4 )

→ F = 80 N

Therefore,

• Force acting on the body is 80 Newtons.