A constant net force acts on an object moving in a straight line - NSC Physical Sciences - Question 1 - 2021 - Paper 1

In this scenario, since a constant net force is acting on the object, it suggests that the object's acceleration is constant (by Newton's second law). However, since acceleration is not constant, we examine the choices:

• Velocity cannot remain constant because the object is accelerating.
• Momentum (which is dependent on both mass and velocity) will change due to the change in velocity as the object accelerates.
• Acceleration is constant as stated, hence cannot be the answer.
• Kinetic energy will change since it is directly related to the square of the velocity (KE = 1/2 mv²), which is changing.

Thus, the quantity that remains constant during the motion, despite the external force acting on the object, is the mass, but not explicitly listed as one of the options.