4. Complete Activity 8.4 (Page 96).
• Request two children to stand on two separate carts as shown in Fig. 8.13.
• Give them a bag full of sand or some other heavy object. Ask them to play a game of catch with the bag.
• Does each of them experience an instantaneous force as a result of throwing the sand bag?
• You can paint a white line on cartwheels to observe the motion of the two carts when the children throw the bag towards each other.
Now, place two children on one cart and one on another cart. The second law of motion can be seen, as this arrangement would show different accelerations for the same force.
Answer:
Aim: To observe what happens when you play catch in both situations and conclude based on that.
Materials Required: Two carts, three children, bag of sand.
Procedure:
(i) The cart can be constructed by using a 12 mm or 18 mm thick plywood board of about 50 cm × 100 cm with two pairs of hard ball-bearing wheels.
(ii) The two children should stand on two separate carts.
(iii) Hand one of them the bag of sand and tell them to play catch by throwing the sandbag back and forth. Observe what happens.
(iv) You can paint a white line on the cartwheels which will help in observing the motion of the two carts.
(v) Now repeat the activity with two children on one cart and one on another cart.
Observations:
- In the first case, the acceleration for both carts is the same.
- In the second case, the acceleration for the cart carrying two children is lesser than the cart carrying a single child.
Conclusions:
- In the first case, the child who throws the bag experiences an equal and opposite force in the opposite direction (Newton’s third law). The other child who catches the bag experiences the same force. Since their masses are almost same, the accelerations are almost the same, according to Newton’s second law.
- In the second case, the cart with two children experiences an equal and opposite force in the backward direction (Newton’s third law). The child who catches the bag experiences the same force. Since, the mass is greater than the cart with the single child, the acceleration is lesser even through the forces are equal (Newton’s second law).
“• Request two children to stand on two separate carts as shown in Fig. 8.13.
• Give them a bag full of sand or some other heavy object. Ask them to play a game of catch with the bag.
• Does each of them experience an instantaneous force as a result of throwing the sand bag?
• You can paint a white line on cartwheels to observe the motion of the two carts when the children throw the bag towards each other.
Now, place two children on one cart and one on another cart. The second law of motion can be seen, as this arrangement would show different accelerations for the same force.” – Solved.
Related Links:
Solution to Activity 8.1
Solution to Activity 8.2
Solution to Activity 8.3
Solution to Activity 8.4
Solution to Chapter 8 Force and Laws of Motion
