Question

he mass of a body is 40 kg . It is moving with a speed of 60 m/s. Calculate its kinetic energy. *

Answer 1

Answer:

48

Explanation:

Given,

m

1

=40kg,v

1

=4m/s,m

2

=60kg,,v

2

=2m/s

Since the body is inelastic, both masses would move together at the velocity v,

According to the conservation of momentum,

m

1

v

1

+m

2

v

2

=(m

1

+m

2

)v

⇒40×4+60×2=(40+60)v

⇒280=100v

⇒v=2.8m/s

So initial KE=0.5×m

1

(v

1

2

)+0.5m

2

(v

2

)

2

=0.5×40×16+0.5×60×4=440J

The final KE=0.5(40+60)2.8

2

=392J

Thus the difference in the kinetic energy =440−392=48