Questions from College Physics

Q: Why is it easier to push open a swinging door from near

Why is it easier to push open a swinging door from near the edge away from the hinges rather than in the middle of the door?

Q: Capacitors are used in many applications where you need to supply a

Capacitors are used in many applications where you need to supply a short burst of energy. A 100.0 µF capacitor in an electronic flash lamp supplies an average power of 10.0 kW to the lamp for 2.0 ms....

Q: A book measures 3 cm by 16 cm by 24 cm.

A book measures 3 cm by 16 cm by 24 cm. About which of the axes shown in the figure is its rotational inertia smallest?

Q: Paula swims across a river that is 10.2 m wide

Paula swims across a river that is 10.2 m wide. She can swim at 0.833 m/s in still water, but the river flows with a speed of 1.43 m/s. If Paula swims in such a way that she crosses the river in as sh...

Q: An object in equilibrium has only two forces acting on it.

An object in equilibrium has only two forces acting on it. The forces must be equal in magnitude and opposite in direction in order to give a translational net force of zero. What else must be true of...

Q: A pinhole camera doesn't have a lens; a small circular hole

A pinhole camera doesn't have a lens; a small circular hole lets light into the camera, which then exposes the film. For the sharpest image, light from a distant point source makes as small a spot on...

Q: Why do many helicopters have a small propeller attached to the tail

Why do many helicopters have a small propeller attached to the tail that rotates in a vertical plane? Why is this attached at the tail rather than somewhere else? [Hint: Most of the helicopter's mass...

Q: If a man has an average useful power output of 40.

If a man has an average useful power output of 40.0 W, what minimum time would it take him to lift fifty 10.0 kg boxes to a height of 2.00 m?

Q: In the “Pinewood Derby,” Cub Scouts construct cars and then

In the “Pinewood Derby,” Cub Scouts construct cars and then race them down an incline. Some say that, everything else being equal (friction, drag coefficient, same wheels, etc.), a heavier car will wi...

Q: Four brass wires are subjected to the same tensile stress. The

Four brass wires are subjected to the same tensile stress. The wires have unstretched lengths and diameters as follows. Rank the four wires in decreasing order of the amount of stretch. (a) length L,...