A body moves with constant speed in a straight line.Which of the following statements must be true?
A)No force acts on the body.
B)A single constant force acts on the body in the direction of motion.
C)A single constant force acts on the body in the direction opposite to the motion.
D)A net force of zero acts on the body.
E)A constant net force acts on the body in the direction of motion.

Question

Quizplus · Accepted Answer

If a body is moving in a straight line with constant speed, it means that the acceleration of the body is zero. According to Newton's second law of motion, the acceleration of an object is directly proportional to the net force acting on it. Therefore, if the acceleration is zero, the net force acting on the body must also be zero. Hence, option D, a net force of zero acts on the body, must be true. Options A, B, C, and E are incorrect as they imply the presence of a force acting on the body, which is not possible if the body is moving with a constant speed in a straight line.

A Body Moves with Constant Speed in a Straight Line