Question

A body of mass 3 kg is under a constant force which causes a displacements in 1 metre in it, given by the relation s=1/3 t2
where t is in second. Work done by the
force in 2 seconds is​

Answer 1

Explanation:

By using work energy theorem

W = ΔKE =

2

1

mv

2

2

-

2

1

mv

1

2

Now s =

3

1

t

2

⇒ v =

3

2

t

⇒ v

1

= 0, v

2

=

3

2

× 2 =

3

4

ms

−1

Answer 2

Answer:

By using work energy theorem

$W = KE = \frac{1}{2}mv ^{2}_{2} -\frac{1}{2}mv ^{2} _{1} \\Now s =\frac{1}{3}t ^{2} => v=\frac{2}{3}t\\=>v_{1} =0,v_{2}=\frac{2}{3}*2=\frac{4}{3}m^{-1} \\Therefore W = \frac{1}{2}*3[\frac{4}{3}] ^{2} -\frac{1}{2} *3*[0]^{2} \\=\frac{8}{3}$

 

Explanation: