English Medium कक्षा ९ - CBSE Question Bank Solutions for Science

How much work is done when a force of 1 N moves a body through a distance of 1 m in its own direction?

Define the term 'work'. Write the formula for the work done on a body when a force acts on the body in the direction of its displacement. Give the meaning of each symbol which occurs in the formula.

A person of mass 50 kg climbs a tower of height 72 metres. Calculate the work done. (g = 9.8 m s⁻²).

When do we say that work is done? Write the formula for the work done by a body in moving up against gravity. Give the meaning of each symbol which occurs in it.

How much work is done when a force of 2 N moves a body through a distance of 10 cm in the direction of force?

What happens to the work done when the dispacement of body is at right angles to the direction of force acting on it? Explain your answer.

A force of 50 N acts on a body and moves it a distance of 4 m on horizontal surface. Calculate the work done if the direction of force is at an angle of 60° to the horizontal surface.

The work done by a force acting obliquely is given by the formula : W = F cos θ ✕ s. What will happen to the work done if angle θ between the direction of force and motion of the body is increased gradually? Will it increase, decrease or remain constant.

What should be the angle between the direction of force and the direction of motion of a body so that the work done is zero?

In which of the following case the work done by a force will be maximum : when the angle between the direction of force and direction of motion is 0° or 90°?

How much work is done by the gravitational force of earth acting on a satellite moving around it in a circular path? Give reason for your answer.

A max X goes to the top of a building by a vertical spiral staircase. Another man Y of the same mass goes to the top of the same building by a slanting ladder. Which of the two does more work against gravity and why?

A boy tries to push a truck parked on the roadside. The truck does not move at all. Another boy pushes a bicycle. The bicycle moves through a certain distance. In which case was the work done more : on the trick or on the bicycle? Give a reason to support your answer.

In case of negative work, the angle between the force and displacement is :

A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. If the value of g be 10 m/s², the work done by the girl against the gravitational force will be :

The work done on an object does not depend on the :

Each of the following statement describes a force acting. Which force is causing work to be done?

A girl weighing 400 N climbs a vertical ladder. If the value of g be 10 m s⁻², the work by her after climbing 2 m will be :