Question

A force increases the speed of a 1.0 kg object from 4 m/s to 8 m/s. How much work done by the force ?

Answer 1

force=mass×acceleration

force=1×8=8N

work done = displacement × force

; =8×8

=64J

Answer 2

Answer:

The work done by the force is 24 J.

Explanation:

Given that,

Mass of object = 1.0 kg

Initial speed = 4 m/s

Final speed = 8 m/s

We need to calculate the work done by the force

Using change in kinetic energy

$W=\Delta K.E$

$W=\dfrac{1}{2}mv_{f}^2-\dfrac{1}{2}mv_{i}^2$

Where, $v_{i}$ = initial velocity

$v_{f}$ = final velocity

Put the value into the formula

$W=\dfrac{1}{2}\times1.0\times8^2-\dfrac{1}{2}\times1.0\times4^2$

$W=24\ J$

Hence, The work done by the force is 24 J.