1. Complete Activity 11.1 (Page 127).
• Take a tuning fork and set it vibrating by striking its prong on a rubber pad. Bring it near your ear.
• Do you hear any sound?
• Touch one of the prongs of the vibrating tuning fork with your finger and share your experience with your friends.
• Now, suspend a table tennis ball or a small plastic ball by a thread from a support [Take a big needle and a thread, put a knot at one end of the thread, and then with the help of the needle pass the thread through the ball]. Touch the ball gently with the prong of a vibrating tuning fork (Fig. 11.1).
• Observe what happens and discuss with your friends.
Answer:
Aim: To hear and touch the vibrating tuning fork and also observe what happens when you touch the ball gently with the tuning fork and conclude based on that.
Materials Required: Tuning fork, rubber pad, table tennis ball, thread, support, needle.
Procedure:
(i) Strike the prong of the tuning fork against the rubber pad and bring it near your ear. Note the observations.
(ii) Touch the vibrating prong with your finger and discuss the observations.
(iii) Suspend the table tennis ball from the support.
(iv) Now strike the prong of the tuning fork again and touch the ball gently with the prong. Note the observations.
Observations:
- When you bring the prong of the tuning fork near your ear, you will hear a faint sound.
- When you touch the vibrating prong with your finger, you will feel a tingling sensation due to the vibrations.
When the ping pong ball is touched with the prong of the vibrating tuning fork, the ball gets deflected from its original position.
Conclusions:
- We conclude that vibrating objects produce sound energy.
- The ball got deflected from its initial position because the sound energy produced by the tuning fork got converted to kinetic energy of the ball.
“Take a tuning fork and set it vibrating by striking its prong on a rubber pad. Bring it near your ear.
Do you hear any sound?
Touch one of the prongs of the vibrating tuning fork with your finger and share your experience with your friends.
Now, suspend a table tennis ball or a small plastic ball by a thread from a support [Take a big needle and a thread, put a knot at one end of the thread, and then with the help of the needle pass the thread through the ball]. Touch the ball gently with the prong of a vibrating tuning fork (Fig. 11.1).
Observe what happens and discuss with your friends.” – Solved.
Related Links:
Solution to Activity 11.1
Solution to Activity 11.2
Solution to Activity 11.3
Solution to Activity 11.4
Solution to Activity 11.5
Solutions to Chapter 11 Work and Energy
