Questions from College Physics

Q: A boat that can travel at 4.0 km/h

A boat that can travel at 4.0 km/h in still water crosses a river with a current of 1.8 km/h. At what angle must the boat be pointed upstream to travel straight across the river? In other words, in wh...

Q: A playground merry-go-round (see Fig. 8

A playground merry-go-round (see Fig. 8.5) spins with negligible friction. A child moves from the center out to the rim of the merry- go-round platform. Let the system be the merry-go-round plus the c...

Q: The potential difference across a cell membrane is −90 mV.

The potential difference across a cell membrane is −90 mV. If the membrane's thickness is 10 nm, what is the magnitude of the electric field in the membrane? Assume the field is uniform.

Q: The figure shows a balancing toy with weights extending on either side

The figure shows a balancing toy with weights extending on either side. The toy is extremely stable. It can be pushed quite far off center one way or the other but it does not fall over. Explain why i...

Q: Explain why the posture taken by defensive football linemen makes them more

Explain why the posture taken by defensive football linemen makes them more difficult to push out of the way. Consider both the height of the center of gravity and the size of the support base (the ar...

Q: The center of gravity of the upper body of a bird is

The center of gravity of the upper body of a bird is located below the hips; in a human, the center of gravity of the upper body is located well above the hips. Since the upper body is supported by th...

Q: The forces required to extend a spring to various lengths are measured

The forces required to extend a spring to various lengths are measured. The results are shown in the following table. Using the data in the table, plot a graph that helps you to answer the following t...

Q: An astronaut wants to remove a bolt from a satellite in orbit

An astronaut wants to remove a bolt from a satellite in orbit. He positions himself so that he is at rest with respect to the satellite, then pulls out a wrench and attempts to remove the bolt. What i...

Q: Your door is hinged to close automatically after being opened. Where

Your door is hinged to close automatically after being opened. Where is the best place to put a wedge-shaped door stopper on a slippery floor in order to hold the door open? Should it be placed close...

Q: In this problem, you can show from Coulomb’s law that the

In this problem, you can show from Coulomb’s law that the constant of proportionality in Gauss’s law must be 1/ϵ0. Imagine a sphere with its center at a point charge q. (a) Write an expression for th...