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

$K = 10 J$