Question

A body of mass 5kg is moving with a velocity 10m/s. Now a force delivers constant power of 75 watt is applies on it for 10s in same direction. Then the final velocity of body after 10s is

Answer 1

Answer:

20 m/sec

Explanation:

cal Work done =750j

w=∆KE

then cal v2

Answer 2

The final speed of the body is 20 m/s.

Explanation:

Given that,

Mass of the body, m = 5 kg

Initial speed of the body, u = 10 m/s

Power applied to a body, P = 75 W

Time, t = 10 s

To find,

The final velocity of body after 10 s.

Solution,

The power delivered by an object is given by energy per unit time. Energy is given by :

$E=P\times t$

$E=75\times 10$

E = 750 J

Since, work done is equal to the change in kinetic energy. It is given by :

$W=\dfrac{1}{2}m(v^2-u^2)$

$v^2=\dfrac{2W}{m}+u^2$

$v^2=\dfrac{2\times 750}{5}+(10)^2$

v = 20 m/s

So, the final speed of the body is 20 m/s.

Learn more,

Work energy theorem

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