Question

Which one is an INCORRECT statement?

• A. Forces always occur in pairs
• B. Impulsive force is a force that acts for a shorter duration
• C. Impulse is the change in momentum of the body
• D. Momentum and change in momentum both have the same direction
• E. Action and reaction forces act on different bodies

Hint:

While momentum and change in momentum are related, they do not always point in the same direction because the force causing the change may alter the direction of motion.

Answer 1

The Correct Option is D

Let's analyze each statement:
(A) Forces always occur in pairs:
- This is a true statement. According to Newton's Third Law, forces always occur in pairs, known as action and reaction forces, which act on different bodies but are equal in magnitude and opposite in direction.
(B) Impulsive force is a force that acts for a shorter duration:
- This is also true. Impulsive forces are forces that act over a very short time interval but cause a significant change in momentum.
(C) Impulse is the change in momentum of the body:
- This statement is true. Impulse is indeed the change in momentum of an object and is given by 
\( {Impulse} = F \Delta t = \Delta p \), where \( \Delta p \) is the change in momentum.
(D) Momentum and change in momentum both have the same direction:
- This is incorrect. Momentum is a vector quantity that depends on the velocity and direction of motion of an object. The change in momentum, however, depends on the force applied and the direction of the force. Momentum and change in momentum do not necessarily point in the same direction, especially when external forces cause a change in the direction of motion.
(E) Action and reaction forces act on different bodies:
- This is true. According to Newton's Third Law, action and reaction forces act on different bodies but are equal in magnitude and opposite in direction.
Thus, the incorrect statement is option (D), "Momentum and change in momentum both have the same direction."