Question

a force of 4n is applied on a body of mass 20 kg the work done in 3rd second is

Answer 1

Answer:

3.6 J

Explanation:

Force = 4N and mass of body = 20 kg

Time at which work needs to be found = 3rd second

Force(f) = Mass(m) x Acceleration(a)

Therefore, Acceleration(a) = Force/Mass = 4/20 = 1/5 ms⁻² = 0.2 ms⁻²

Taking Intial velocity (u) = 0 ms⁻¹

Displacement =  ut+1/2at² = 0.5 x 0.2 x 3² = 0.1 x 9 = 0.9 m

Work = Force x Displacement = 4 x 0.9 =3.6 J

Answer 2

Answer:

Explanation:

F=ma.....

a=F/m..... 4/20=1/5

Distance traveled in 1st.,2nd, 3rd.. Is in the ratio

1:3:5..

So...Sn=u+a/2(2n-1)

Taking initial velocity u=0

S3=1/10(5)=1/2

W=F.s

W=4.1/2=2

W=2J