Question

Which one of the following statement is INCORRECT?

• A. The state of rest or uniform linear motion both imply zero acceleration.
• B. Momentum is a vector quantity.
• C. Inertia means resistance to change.
• D. The rate of change of momentum is proportional to the applied force.
• E. A net force is needed to keep a body in uniform motion.

Answer 1

Answer: (E)

We are given the following statements, and we need to identify which one is incorrect:

• The state of rest or uniform linear motion both imply zero acceleration: This is correct. According to Newton's first law of motion, when a body is at rest or moving with uniform velocity, it has zero acceleration.
• A net force is needed to keep a body in uniform motion: This is incorrect. In the case of uniform motion (in a straight line), no net force is required to keep the body moving. According to Newton's first law, an object in motion will stay in motion with constant velocity unless acted upon by an external force.
• Inertia means resistance to change: This is correct. Inertia refers to an object's tendency to resist changes in its state of motion (either rest or uniform motion).
• The rate of change of momentum is proportional to the applied force: This is correct. According to Newton's second law, the rate of change of momentum is directly proportional to the applied force.
• Momentum is a vector quantity: This is correct. Momentum is a vector quantity because it has both magnitude and direction, which are dependent on the velocity of the object.

Correct Answer:

Correct Answer: (E) A net force is needed to keep a body in uniform motion