Question

Velocity of a particle of mass 1 kg moving rectilinearly is given by v =$25-2t+t^2$. Find the average power of the force acting on the particle between time interval t = 0 to t = 1 sec.

• A. 49 W
• B. 24.5W
• C. - 49 W
• D. -24.5 W

Answer 1

Answer: (D)

-24.5 W

Velocity os the object is given by equation

$u=25-2t+t^2$

Now,

velocity at $t=0$

$v_i=25m/s$

velocity at $t=1$

$v_f=24m/s$

now work done by all forces is given by:

$W=\frac{1}{2}mv{f}^2-\frac{1}{2}m{v}_i^3$

$W=\frac{1}{2}\times 1\times (24{)}^2-(25{)}^2$

$W=24.5J$

now power is given:

$P=\frac{W}{t}$

here $t=1s$

$P=\frac{24.5}{1}$

$W=24.5$ watt

Hence,