Question

The velocity of a body of mass $2kg$ varies according to the equation $v=(10S–3)m/s$ where $S$ is the displacement of the body (in $m$). Find the force acting on the body at the instant when it has undergone a displacement of $2m$.

• A. $170N$
• B. $340N$
• C. $510N$
• D. $170N$

Answer 1

The correct option is B $340N$

$v=(10S-3)m/s$
Acceleration of body at the instant when it has undergone a displacement of $S=2m$ can be calculated by using
$a=v\frac{dv}{dS}=(10S–3)\times 10=170m/s^2$
Hence, from Newton's second law,
$F=ma=2\times 170=340N$