Question

A force of 5 N acts on a 15 kg particle initially at rest . What will be instantaneous power due to the force at the end of $6^{th}$ second.

• A. 10 watt
• B. 5 watt
• C. 20 watt
• D. 25 watt

Answer 1

The correct option is A 10 watt

Given that

A force $F=5N$ acts a man $m=15kg$ initial at rest $(u=0)$

From Newton's second law

acceleration of object: $a=\frac{F}{m}=\frac{5}{15}=\frac{1}{3}m/s^2$

Now from kinematies

$v=u+at$

At end of $t=6s$, velocity will be:-

$v=0+\frac{1}{3}\times 6=2m/s$

so instantenous power delived by force:

$P=Fv=5\times 2=10w$