Question

A cricket ball hits and breaks a glass window and ends up inside the house. Identify which of the following statements is correct about the ball?
A) The force the ball exerted on the window was larger than the force the window exerted on the ball.
B) The force the ball exerted on the window was smaller than the force the window exerted on the ball.
C) The force the ball exerted on the window was the same as the force the window exerted on the ball.
D) Since the ball broke the window, it did not lose any momentum.
E) The kinetic energy the ball had before it broke the window equalled the kinetic energy the ball had after it broke the window.

Answer 1

To solve this question we apply Newton's third law and the conservation of momentum.

Complete step by step solution:
When a cricket ball hits the wall, the magnitude of the force exerted by the cricket ball on the wall is equal to the force exerted by the wall on the ball, but opposite in the direction of force. This idea was first given by the scientist Newton. This theory is known as Newton’s first law. As per Newton third law, if a body exerts a force on another body, another body will exert an equal force on the first body. In this case it is given that a cricket ball hits and breaks a glass and ends up inside the house. Here also the force applied by ball on glass and force applied by glass window on the bullet is equal in magnitude.

Now, we analyse each option in detail.
Option A: In the option it is given that the force the ball exerted on the window was larger than the force the window exerted on the ball, which is not possible as per Newton’s third law. Hence this option is wrong.

Option B: Here it is given that the force the ball exerted on the window was smaller than the force the window exerted on the ball. Again, this also is not true as per Newton’s third law.

Option C: The force the ball exerted on the window was the same as the force the window exerted on the ball, which is true as per Newton’s third law. Hence, this is the correct answer.

Option D: The total momentum of the system remains the same which is known as conservation of momentum. As per this law, the momentum lost by the bullet utilized to break the glass window. Hence total momentum does not change at all, it remains constant. In this option given that the ball broke the window, it did not lose any momentum. Hence this is also not true as per conservation of momentum.

Option E: The kinetic energy the ball had before it broke the window equalled the kinetic energy the ball had after it broke the window. Again, this is not true. Because the speed of the bullet decreases once it collides the glass window, which in turn decreases the kinetic energy of the bullet. This option is also not true.

The correct answer is option C. A cricket ball hits and breaks a glass window and ends up inside the house. The force the ball exerted on the window was the same as the force the window exerted on the ball.

Note: Action and reaction forces cancel each other when they act on the same body. When it acts on two different bodies it does not cancel the force.