### Q.9:- A body is initially at rest. It undergoes one-dimensional motion with constant acceleration. The power delivered to it at time *t *is proportional to

(i) *t*^{1/2} (ii) *t* (iii) *t*^{3/2} (iv) *t*^{2}

**Answer:-**

From,

*v* = *u* + *at*

*v* = 0 + *at* = *at*

As power, *P* = *F* × *v*

∴ *P* = (*ma*) × *at* = *ma*^{2}*t*

As *m* and *a* are constants, therefore, *P* ∝ *t*

Hence, right choice is (ii)* t*