Question

a) 12 b) 144 c) 72 d) 43 20 Joules of work is done in accelerating a 4kg mass from rest across a horizontal frictionless surface. The kinetic energy gained by the mass is: a) 4J d) 50J b) 20J c) 10J​

Answer 1

Explanation:

Correct option is

B

10

4

J

Acceleration that causes the given rise in speed in given time = a=

t

v

=

10 s

20 m/s

=2 m/s

2

Thus, force acting on the body = F=ma=100 N

Distance travelled in the given time = s=

2

1

at

2

=100 m

Thus, work done in given time = F.s=10

4

J