Question

multiple select question
select all that apply
newtons second law contains in it all the information of newtons first law. however, newtons first law is simpler; thus, using the first law instead of the second can simplify an analysis.
which of the following situations are best understood using newtons first law of motion, assuming no unbalanced external forces act on the object?
□ a free falling rock
□ a parked car
□ a car traveling in a straight line on cruise control
□ a car on cruise control turning in a circle

Explanation:

Newton's first law applies to objects with no unbalanced external forces, meaning they are either at rest or moving at constant velocity in a straight line.

1. A free falling rock has gravity (unbalanced force) acting on it, so it accelerates—first law does not apply.
2. A parked car is at rest with no unbalanced forces, so first law applies.
3. A car traveling straight on cruise control moves at constant velocity with no net unbalanced forces, so first law applies.
4. A car turning in a circle has a centripetal (unbalanced) force acting on it, changing its direction—first law does not apply.

Answer:

B. A parked car
C. A car traveling in a straight line on cruise control