Question

In pressing a rubber ball placed on a table, the application of force leads to:
A. A change in the shape of the object.
B. A change in the state of the motion of the object.
C. A change in the mass of the object.
D. No change anywhere.

Answer 1

The concept of force arises from Newton's laws of motion. To solve this question, we do not need the mathematical definition of the force, which is given by these Newton’s laws, but we need the physical significance of the motion i.e. the physical characteristics of force.

Complete step-by-step answer:
Generally speaking, the force is defined as the push or pull experienced by a body. The mathematical definition of force is given by the Newton’s second law of motion which states that, the force is the product of mass and acceleration of the body:

$F = ma$

where m = mass of the body and a = acceleration of the body.
The characteristics of force means the effects that the force can have on a body. There are four characteristics of force. Let us examine them one-by-one.
1. Force can change the state of motion.
Whenever force is applied on a body, the state of motion that it is in, gets changed. If a body is at rest, on application of force, the body starts moving. Similarly, if a body is moving at a uniform speed, it comes to rest when a stopping force is applied.

2. Force can change the direction of motion.
In a football match, whenever a player kicks the moving ball, the direction of the motion of the football changes. We can say that the player has applied force in this case to change the direction of motion of the moving body.

3. Force can change the velocity of a moving body.
This is a direct statement of the second law of motion which states that force is the product of mass and acceleration. Acceleration means nothing but the change in the velocity. So, whenever the velocity of a moving body changes, we can say that the force has been applied to the body.

4. Force can change the shape of the object.
The force, applied on an object, not only alters the motion of the body but also, the shape of the body. The force applied on a body can aid in expanding or compressing a body and hence, changing its physical form, shape, and dimensions. Examples can be found in clay modelling where the force applied is used for molding the clay.
When a rubber ball is pressed on a table, there is force acting on the rubber ball and it compresses the ball and hence, changes its shape and physical structure. Thus, the last characteristic number 4 is the best applicable to this case.
Hence, the characteristic of change in shape of an object is applicable here.

Hence, the correct option is Option A.

Note: When the force is applied, the body does not completely deform. There is an inherent property in the material called elasticity which will help the body to regain the original shape and form, after removing the force. When the force exceeds this limit of elasticity, the force can completely and permanently alter the shape and structure of a body.