A student sits on a stool which is free to rotate about a vertical axis.
He is holding weights in his hands. His arms are extended, holding the
weights as far from his body as possible. Someone gives him a push which
starts him rotating. If he then pulls the weights in close to his
body, he rotates faster. What happens to his rotational
kinetic energy when he pulls
in the weights?
increases
decreases
remains the same
A puck is going around in a circle on a frictionless surface, as shown
in the figure. A string attached to the puck goes through a hole
in the surface, and a student is holding the other end of the string.
If the student pulls some of the string through the hole, what will
happen to the puck and why?
Where is the pressure greater, one meter beneath the surface of Lake
Michigan or one meter beneath the surface of a swimming pool?
in Lake Michigan
in the swimming pool
same
Neglect the difference in the atmospheric pressures above Lake Michigan
and the swimming pool.
A hydraulic arrangement consists of a water-filled U-tube that is wider
on one end than on the other. Pistons are fitted in both ends. To
multiply an input force, which piston should be on the input end?
larger-diameter piston
smaller-diameter piston
It doesn't matter what relative size the
piston is.
When I measure the pressure in a flat tire, the pressure gauge says zero.
Is the pressure inside a flat tire really zero? Explain.