Q2 of 28 Page 159

Give few examples where displacement of an object is in the direction opposite to the force acting on the object.

Example (i)- When a ball thrown upward the Gravitational force acts downward and the direction of motion of ball is upward as shown in Fig-(i).

Example (ii) when a ball rolls over a surface it slows down due to frictional force which acts opposite to the direction of motion of ball as shown in Fig-(ii).



Fig -(i) Fig-(ii)


More from this chapter

All 28 →
1

Define work and write its units.

 3

Identify the wrong statement among the following. Rewrite them by making necessary corrections.

a) Work and energy have different units.


b) When an aero plane takes off, the work done by its weight is positive.


c) The potential energy of spring increases when it is extended and decreases when it is compressed.


d) If the work done by external forces on a system is negative then the energy of the system decreases.


e) When a body is falling freely from a height, its kinetic energy remains constant.


f) The unit of power is watt.

 4

What is mechanical energy?

 5

State the principle of conservation of energy.