Question

question 3 (1 point)
a packing crate slides down an inclined ramp at constant velocity. thus we can deduce that
○ a frictional force is acting on it.
○ a net downward force is acting on it.
○ it may be accelerating.
○ it is not acted on by appreciable gravitational force.

Explanation:

1. Recall Newton's first law: If an object moves at constant velocity, the net force on it is zero ($F_{net} = ma$, and $a = 0$ for constant velocity, so $F_{net}=0$).
2. Analyze forces on the crate: Gravity acts downward, normal force perpendicular to the ramp, and friction (if present) acts up the ramp (opposing motion). For constant velocity, the component of gravity down the ramp must be balanced by friction up the ramp.
3. Evaluate options:

• "a frictional force is acting on it": Since the net force is zero and gravity has a component down the ramp, friction must act up the ramp to balance it. This is correct.
• "a net downward force is acting on it": Net force is zero (constant velocity), so this is wrong.
• "it may be accelerating": Constant velocity means acceleration is zero, so this is wrong.
• "it is not acted on by appreciable gravitational force": All objects near Earth experience gravity, so this is wrong.

Answer:

A. a frictional force is acting on it.