Question

A force F is exerted on a 5 kg block to move it across a rough surface, as shown above. Themagnitude of the force is initially 5 N, and the block moves at a coristant velocity. While the block ismoving, the force is instantaneously increased to 12 N. How much kinetic energy does the block now gain as it moves a distance of 2m.

Answer 1

Given that the mass of the block is m = 5 kg

The total force is F = 5+12 = 17 N

The displacement of the block is d = 2 m

We have to find the gain in kinetic energy.

The gain in kinetic energy is given by the formula

$\begin{gathered} \Delta K\mathrm{}E\text{. = work done} \\ =F\times d \end{gathered}$

Substituting the values, the gain in kinetic energy will be

$\begin{gathered} \Delta K.E.=17\times2 \\ =34\text{ J} \end{gathered}$

Thus, the gain in kinetic energy is 34 J