An amusement park ride moving down with a constant velocity is an example of a non-inertial frame of reference.

Suppose a child is riding on a merry-go-round at a distance about halfway between its center and edge. She has a lunch box resting on wax paper, so that there is very little friction between it and the merry-go-round. Which path shown below will the lunch box take when she lets go? The lunch box leaves a trail in the dust on the merry-goround. Is that trail straight, curved to the left, or curved to the right? Explain your answer.

If centripetal force is directed toward the center, why do you feel that you are 'thrown' away from the center as a car goes around a curve? Explain.

Define centripetal force. Can any type of force (for example, tension, gravitational force, friction, and so on) be a centripetal force? Can any combination of forces be a centripetal force?

A horizontal force of 100 N is to be applied to a 10 kg slab that is initially stationary on a frictionless floor, to accelerate the slab. A 10 kg block lies on top of the slab; the coefficient of friction $\mu$ between the block and the slab is not known, and the block might slip.

What is the possible range for the magnitude $a_{\text {block }}$ of the block's acceleration?

A horizontal force of 100 N is to be applied to a 10 kg slab that is initially stationary on a frictionless floor, to accelerate the slab. A $10 \mathrm{~kg}$ block lies on top of the slab; the coefficient of friction $\mu$ between the block and the slab is not known, and the block might slip. Considering that possibility, what is the possible range of values for the magnitude of the slab's acceleration $a_{\text {slab }}$ ? (Hint: You don't need written calculations; just consider extreme values for $\mu$.)

In the given figure a block of mass $m$ is held stationary on a ramp by the frictional force on it from the ramp. A force $\vec{F}$, directed up the ramp, is then applied to the block and gradually increased in magnitude from zero. During the increase, what happens to the direction and magnitude of the frictional force on the block?

If you wish to reduce the stress (which is related to centripetal force) on high-speed tires, would you use large- or small-diameter tires? Explain.

Can centripetal acceleration change the speed of circular motion? Explain.

Which of the following describes a situation explained by Newton's third law? (a) a person pushes left on a wall while the wall pushes right on a person (b) clothes in a washing machine moving to the edge of the drum during the spin cycle (c) a spacecraft moving far from any massive bodies (d) a car accelerating forward by an amount equal to the ratio of the net forward force and the mass of the car

A space station has a radius of $100 \mathrm{~m}$. (a) What period of rotation is needed to provide an artificial gravity of $g$ at the rim? (b) At what speed is the rim moving? (c) What is your apparent weight if you run along the rim at $4.2 \mathrm{~m} / \mathrm{s}$ opposite the rotation direction? (d) What is your apparent weight if you instead run in the direction of rotation? (e) In which direction would you run to get the best workout, with or against the rotation? Or does it matter?

The velocity-time graph in Figure mentioned the change in velocity for a truck. (a) At what point is the instantaneous velocity of the truck equal to the average velocity? (b) Determine the magnitude of the acceleration of the truck from the graph in Figure mentioned.

Two athletes compete in the hammer throw. One athlete can spin the hammer twice as fast as the second athlete. Compare the magnitudes of the two centripetal accelerations for the two hammer throws. Explain your answer.

The light wave inside the tube of a laser is a standing wave, reflected at both ends of the tube. If the distance between the ends is $L$, what condition must the wavelength of the standing wave satisfy?