Q1 of 15 Page 49

Observe the figures given below. Answer the following questions.


a) When the card is suddenly struck off, what happens to the coin? Explain.


b) What is the law to which this property is related?


c) How is the property related to the mass of the object?

The figures given below tells about the impact of forces, the left figure tells the moment before the force is applied and the right hand side figure tells us about the moment after force has been applied. The force applied is fast, that is the force was applied within a very short interval of time (IMPULSE).

(a). When the card is suddenly(short interval of time) struck off from it’s rest position, that is force was applied on card, not on coin,


The coins remains at the same position, and does not changes it’s position unlike the card but falls from it’s original position where it was kept and it falls simply vertically, also there is no change in it’s position in horizontal way. The coin falls freely.


The coin falls as if it was dropped from it’s same position.


The reason behind this type of behavior of the coin is due to INERTIA which depends upon mass.


This type of inertia is called inertia of rest which means that when a body is at rest it remains at rest.


So that’s what the coin does.


(b). This property inertia(rest) is related to Newton’s first law of motion which tells us that “ When a body is at motion it remains in motion in one direction and with constant velocity and when a body is at rest it remains at rest until there is an external force applied on the body. ” .


(c). The property INERTIA is directly proportional to the mass of the object, that is the body having large mass will have large inertia and the body having small mass will have small inertia.


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