+91-8076753736 [email protected]

-->

Work, Energy And Power

Question

Wired Faculty App

A particle of mass 100 g is thrown vertically upwards with a speed of 5 m/s. The work done by the force of gravity during the time the particle goes up is

-0.5 J

-1.25 J

1.25 J

0.5 J

Solution

B.

-1.25 J

The height (h) traversed by particle while going up is

$h = \frac{u^{2}}{2 g} h = \frac{25}{2 \times 9.8}$

$Work done by gravity force = m \vec{g} . \vec{h} = 0.1 \times g \times \frac{25}{2 \times 9.8} \cos 180^{o}$

[Angle between force and displacement is 180°)

$W = - 0.1 \times \frac{25}{2}$

⇒ W = -1.25 J

Some More Questions From Work, Energy and Power Chapter

Does the body at rest possess energy?

By eating two apples, a person starts pushing the wall of room. If food value of apple is 100 calories per apple, how much work he will do in pushing the wall in one hour?

A man is rowing upstream and is at rest w.r.t. shore. Is he doing work w.r.t. shore?

Is frictional force conservative?

What is the work done by gravitational force in taking the mass m with constant velocity through height h?

A mass is tied with a string and whirled in horizontal circle. What is the work done by tension force?

Does the work done by force depend upon the velocity at that instant?

What is the work done by man against gravity when he is carrying a load on his head and walking on the horizontal road?

Are all central forces conservative?

Mock Test Series

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation