Rock is whirled around in a circle with a slingshot. As the rock leaves the slingshot, it has an instantaneous velocity in a straight line. How do Newton's laws of motion explain this?

Answer: i) a net force, supplied by the slingshot is acting on the rock as it is whirled around in a circle, and, ii) when the net force ceases, because the rock leaves the slingshot, the rock will move at the instantenous velocity in straightline.

Explanation:

The set of choices is important as twho Newton's laws of motion can explain both the circle path and the straight line path.

You can base your analysis in both the first and second laws of Newton, since the first law is a particular case of the second law.

The circular motion is a change of velocity, since the velocity changes direction continuosly. Change of velocity is acceleration.

As per Newton's first law, if not force is applied, the object will not change its motion: the object will remain at rest or in uniform rectilinear motion, unless a net force acts on it.

As per, Newton's second law force = mass * acceleration. So, the acceleration is zero (not change of velocity) if and only if the net force is zero.

Then, from both laws you conclude that a net force, supplied by the slingshot is acting on the rock as it is whirled around in a circle, and when the net force ceases, because the rock leaves the slingshot, the rock will move at the instantenous velocity in straightline.

The answer is D i just had the question and it was right.