Question

define work done for class 9th chapter work and energy

Answer 1

Ordinarily, by the word work, we mean any kind of mental and physical activities. But in physics, work or mechanical work has a different meaning. According to the scientific definition of work, we say that work has been done on an object when some force is being applied on the object and the object covers a distance due to the applied force and the direction of the distance is same as the direction of the applied force.

To say that Work is done -

1. A Force has to be applied on the object.
2. The object must undergo some displacement along the direction of force.

No work is said to be done if any one of the above two conditions does not exist.

So we come to a conclusion that -

Work is said to be done by a force acting on an object if the applied force causes a displacement of the object.

Answer 2

Work done on an object is defined as the magnitude of the force multiplied by the distance moved by the object in the direction of the applied force. work done by the force does not depend on the time taken in the displacement of point of action.