A ship travelling at $39.0 \mathrm{~km} / \mathrm{h}[\mathrm{N}]$ across the St. Lawrence Seaway encounters a current of $13.0 \mathrm{~km} / \mathrm{h}\left[\mathrm{E} 50.0^{\circ} \mathrm{N}\right]$. What is the velocity of the ship with respect to the shore? (a) $48.4 \mathrm{~km} / \mathrm{h}\left[\mathrm{E} 78.1^{\circ} \mathrm{N}\right]$ (b) $48.4 \mathrm{~km} / \mathrm{h}\left[\mathrm{E} 11.9^{\circ} \mathrm{N}\right]$ (c) $49.7 \mathrm{~km} / \mathrm{h}\left[\mathrm{E} 80.3^{\circ} \mathrm{N}\right]$ (d) $49.7 \mathrm{~km} / \mathrm{h}\left[\mathrm{E} 9.7^{\circ} \mathrm{N}\right]$

When will a bathroom scale with nothing on it read zero? (a) on the ground (b) in an elevator moving up (c) in an elevator moving down (d) in space

The centripetal acceleration of a car moving around a circular curve at a constant speed of $22 \mathrm{~m} / \mathrm{s}$ has a magnitude of $7.8 \mathrm{~m} / \mathrm{s}^2$. Calculate the radius of the curve.

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

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.

Consider the different topics you have studied in this chapter. Choose one that you feel has an important impact on your life. Write a one-page report about the topic, explaining why it is important to you. What else would you like to know about this topic? How could you go about learning this?

The position-time graph in Figure 6 describes the westward motion of a car. (a) From the graph, estimate the total displacement of the car. (b) From the graph, estimate the average velocity of the car.

How has your understanding of uniform circular motion changed? Did you learn anything particularly relevant to you on this topic?

A cylindrical spacecraft rotates around its axis. (a) Explain how rotating a spacecraft produces artificial gravity. (b) Explain how the spacecraft could be used to simulate the gravity an astronaut would experience on Earth.

Prepare a Know-Want to Know-What You Learned (K-W-L) chart on the topic of artificial gravity or another topic from this chapter.

A spacecraft moves with constant speed in a circular orbit around a planet. Then the spacecraft accelerates in the direction it is moving. Arrange the statements below in the correct order to explain why the distance of the spacecraft from the planet must increase in order to remain in a circular orbit. (a) The centripetal force is provided by gravity, which depends on mass and distance. (b) To offset the increase in speed, the distance must also increase. (c) An acceleration in the direction the spacecraft is moving means that the spacecraft is increasing in speed. (d) The masses of both the spacecraft and the planet are constant, so the distance from the planet must change.

In this chapter, you learned how to solve some types of centripetal force problems. What questions do you still have about solving centripetal force problems?