Question

A body initially at rest has an acceleration of $10\hat{j}m/s^2$. If the force acting on the body is $\overrightarrow{F}=(2\hat{i}+3\hat{j}+5\hat{k})N$, the instantaneous power at $t=5$ s will be:

• A. $100W$
• B. $150W$
• C. $50W$
• D. $200W$

Answer 1

The correct option is B $150W$

A body initially at rest has an acceleration of $10\hat{j}m/s^2$.

If the force acting on the body is: $F=(2\hat{i}+3\hat{j}+5\hat{k})N$, then the instantaneous power at t = 5seconds will be:

Given: $\overrightarrow{a}=10\hat{j}m/s^2$, $\overrightarrow{F}=(2\hat{i}+3\hat{j}+5\hat{k})N$

And we know that: $Power=\overrightarrow{F}.\overrightarrow{v}=(2\hat{i}+3\hat{j}+5\hat{k}).(10\hat{j}\times 5)=150W$

Thus, instantaneous power at $t=5$ seconds $=150W$