Question

A boy slides a book across the floor, using a force of 5 N over a distance of 2 m. What is the kinetic energy of the book after he slides it? Assume there is no friction.

A. 20 J
B. 10 J
C. 5 J
D. 2.5 J

Answer 1

As we know from work energy theorem that work done by external force is change in kinetic energy

So from all above we can say

`W = k_f - K_i`

in order to find work done we can say

`W = F.d`

here we have

`F = 5 N`

`d = 2 m`

so we will have

`W = (5)(2) J`

`W = 10 J`

so from above equation we can say that final kinetic energy will be same as work done

so we will have kinetic energy as

`K = 10 J`