Question

A force $F$ acts horizontally on a block of mass $m$ that is initially at rest on a smooth horizontal floor. The force acts for a time $t$ and moves the block a displacement $d$.
Find out the change in the kinetic energy of the block ?

• A. $Fd$
• B. $\frac{F}{d}$
• C. $Ft$
• D. $\frac{F}{t}$
• E. $\frac{d}{t}$

Answer 1

The correct option is A $Fd$

Work done by a force $W=Fd$ $cos\theta$ where $\theta$ is the angle between $d$ and $F$

Here $\theta =0^o$ $⟹W=Fd$ $(\because cos{0}^o=1)$

Using work-energy relation : $W=\Delta K.E$

$⟹$ $\Delta K.E=Fd$