Sports and Second Law of Motion
1. A cricket player or fielder moves his hands backward while catching a fast cricket ball. This allows the fielder to catch the ball by applying a small force on it. If you keep your arms still while catching, the fielder has to apply a larger force on the ball. When we pull arms back with the ball. We apply a smaller force for a longer time. This is because the ball stops completely only when the hands stops moving.
Explanation: Suppose the ball is moving with a speed u. When it stops completely, its speed is v = 0.Suppose ,in the first case, when you pull your arms back, it takes time to stop the ball. The acceleration of the ball in this period is
Similarly, if the time taken to stop the ball is in the second case,
The force in the two cases are
and
As is much larger than , that force is much larger than . A cricket coach, therefore , advise you to pull back your arms while taking a catch, as this would be easier.
2. When an athlete jumps from a height on a hard surface, he can hurt his feet.
Explanation:
This is because the feet come to rest in a very short time and hence the force exerted on the feet is high. That is why athletes during high jump land on sand or foams. This increases the time in which the body comes to rest. The sand gives way allowing the body to slow down gradually.
A passenger in a moving train tosses a coin which falls behind him. Observing this statement what can you say about the motion of the train ? | |||
Right Option : A | |||
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A goalkeeper in a game of football pulls his hands backwards after holding the ball shot at the goal. This enables the goalkeeper to ___________________
| |||
Right Option : D | |||
View Explanation |
The unit of measuring the momentum of a moving body is ______ | |||
Right Option : C | |||
View Explanation |
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