A spinning figure skater pulls his arms in as he rotates on the ice as he pulls his arms in. What happens to his angular momentum L and kinetic energy Ek?

A coin is placed on a vinyl stereo record that is making 33⅓ revolutions per minute on a turntable. In what direction is the acceleration of the coin?

A ball is released from rest on a no-slip surface, as shown. After reaching its lowest point, the ball begins to rise again, this time on a frictionless surface. Assume the ball is a solid sphere of radius $2.9 \mathrm{~cm}$ and mass $0.14 \mathrm{~kg}$. If the ball is released from rest at a height of $0.78 \mathrm{~m}$ above the bottom of the track on the no-slip side. How high does the ball rise on the frictionless side?

A ball is released from rest on a no-slip surface, as shown. After reaching its lowest point, the ball begins to rise again, this time on a frictionless surface. Suppose this time a ball is released from rest on the frictionless surface. When the ball comes to rest on the no-slip surface, is its height greater than, less than, or equal to the height from which it was released?

Kendra and her mother plan to ride the carousel. Two horses on the carousel are side by side. For a more exciting ride, should Kendra sit on the inside or the outside? Explain your reasoning.

A person pushes two boxes with a horizontal force of $100$ N. The boxes are on a horizontal frictionless floor as discussed earlier. If the mass of box A is $5$ kg and the mass of box B is $2$ kg, calculate the magnitude of the action-reaction pair between the two boxes.

A North Carolina state law requires that stairs have minimum treads of 9 in. and maximum risers of 8.25 in. According to this law, what is the maximum grade of stairs in North Carolina?

Which of the following can you observe about Venus with the naked eye? Select all that apply.
A. Venus sometimes shines brightly in the eastern sky shortly before dawn.
B. When Venus is brightest, it is visible all night long.
C. Venus is visible at midnight when it is in its full phase.
D. Venus sometimes shines brightly in the western sky shortly after sunset.

What physical quantity is not conserved in an inelastic collision?

Is it possible for a baseball to have more momentum than a truck? Explain.

Why don’t we see an eclipse at every new and full moon? Describe the conditions needed for a solar or lunar eclipse.

If there is going to be a total lunar eclipse tonight, then you know that:
a) the Moon's phase is full.
b) the Moon's phase is new.
c) the Moon is unusually close to Earth.

Match the correct vocabulary word(s) with each definition given.

Match the correct vocabulary word(s) with each definition given.

area of reduced precipitation on one side of a mountain range

The horizontal beam in Fig weighs $190 \mathrm{~N}$, and its center of gravity is at its center. Find the horizontal and vertical components of the force exerted on the beam at the wall.