0
You visited us 0 times! Enjoying our articles? Unlock Full Access!
Question

# A child is moving on a skateboard at the speed of 2 msâˆ’1. After a force acts on him, his speed becomes 3 msâˆ’1. Find the work done by the external force on the child, given the mass of the child is 20 kg.

A

1 J

No worries! Weâ€˜ve got your back. Try BYJUâ€˜S free classes today!
B

10 J

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
C
20 J
No worries! Weâ€˜ve got your back. Try BYJUâ€˜S free classes today!
D
320 J
No worries! Weâ€˜ve got your back. Try BYJUâ€˜S free classes today!
Open in App
Solution

## The correct option is B 10 J Let initial velocity of the child be v1 and final velocity be v2 Given, v1=2 ms−1, v2=3 ms−1 and mass of the child =20 kg. Since the child is in motion, he will have a kinetic energy of mv22, which will be increased after an application of force by an external agent on him. Now, Applying work energy theorem , Work done by the external force on the child =mv222–mv212 =20×(9–4)2 =10×5=50 J

Suggest Corrections
6
Join BYJU'S Learning Program
Related Videos
kinetic Energy
PHYSICS
Watch in App
Explore more
Join BYJU'S Learning Program