1. Complete Activity 9.1 (Page 100).
• Take a piece of thread.
• Tie a small stone at one end. Hold the other end of the thread and whirl it round, as shown in Fig. 9.1.
• Note the motion of the stone.
• Release the thread.
• Again, note the direction of motion of the stone.
Answer:
Aim: To whirl the stone around, observe the motion of the stone and conclude based on that.
Materials Required: Thread, small stone.
Procedure:
(i) Tie a small stone at the end of the piece of thread.
(ii) Hold the other end of the thread and swing it around. Observe the motion of the stone.
(iii) Then release the thread and observe the direction of motion of the stone.
Observations:
- Before the thread is released, the stone moves in a circular path with a certain speed and changes direction at every point.
- When released the stone flies off along a straight line, which is a tangent to the circular path.
Conclusions:
- The force that keeps the body moving along the circular path is acting towards the centre. This force is called the centripetal force.
- This is a model for the motion of the moon around the earth. The centripetal force is provided by the force of attraction of the earth.
“• Take a piece of thread.
• Tie a small stone at one end. Hold the other end of the thread and whirl it round, as shown in Fig. 9.1.
• Note the motion of the stone.
• Release the thread.
• Again, note the direction of motion of the stone.” – Solved.
Related Links:
Solution to Activity 9.1
Solution to Activity 9.2
Solution to Activity 9.3
Solution to Activity 9.4
Solution to Activity 9.5
Solution to Activity 9.6
Solution to Activity 9.7
Solutions to Chapter 9 Gravitation
