Question

A constant force acts on a body of mass m at rest for t seconds and then ceases to act. In next t seconds the body travels a distance x, magnitude of force is:

• A. $\frac{mx}{t^2}$
• B. $\frac{mx}{t}$
• C. mxt
• D. $mx{t}^2$

Answer 1

The correct option is A $\frac{mx}{t^2}$

Given : $u=0$

Let the velocity of body after t seconds be $v$.

Using $v=u+at$ where $a=\frac{F}{m}$

$\therefore$ $v=0+\frac{F}{m}t$ $⟹v=\frac{Ft}{m}$

Distance covered in another t seconds $x=vt$

$\therefore$ $x=\frac{Ft}{m}t$ $⟹F=\frac{mx}{t^2}$