Question

Certain force acting on a 20 kg mass changes its velocity from

5m/s to 2 m/s. Calculate the work done by the force.​

Answer 1

given

m=20kg

v1=5m/s

v2=2m/s

change in kinetic = work. done

w=m/2(v1^2-v2^2)

w=m/2(v1+v2)(v1-v2)

w=10*7*3

w=210j

Answer 2

Hey mate...Here is your answer...

Given,

m= 20kg.

u= 5 m/s

v= 5 m/s

W=1/2mv^2-1/2mu^2

(as there is kinetic energy as the obj. is moving)

W= 1/2*20*(2)^2-1/2*20*(5)^2

W= 10*4-10*25

W= 40-250

W= -210 J (Joule)

(negative sign shows that force is in opposite direction)

Hope this helps........