When a plastic rod is rubbed with a wool cloth, the wool acquires a positive charge. What is the best explanation for this effect?

A brick is resting on the surface of a flat board. as one end of the board is slowly raised, what change, if any, is there in the normal force exerted on the brick?

If your brakes give out, why can't you just pull the keys out of the ignition?

A group of students is investigating whether copper is a better thermal conductor than steel. The students take a copper wire and a steel wire of the same length and diameter.

A rope of negligible mass is wrapped around a 225-kg solid cylinder of radius 0.400 m. the cylinder is suspended several meters off the ground with its axis oriented horizontally, and turns on that axis without friction. (a) if a 75.

Which of the following situations is an example of change in momentum? a. a tennis ball hit into a net b. a helium ballon rising up into the sky c. an airplane flying through scattered clouds

Why do two hydrogen atoms bond to form a hydrogen molecule

Suppose the gravitational force between two spheres is 100 N. If the distance between the spheres is halved, what is the new gravitational force between them?

Ilya and Anya each can run at a speed of 8.00 mph and walk at a speed of 3.20 mph. They set off together on a route of length 5.00 miles.

Jill is getting ready to push little Frank in his swing. She pulls Frank back as high as she can and then releases the swing. What is the initial transfer of energy that accelerates the swing when she lets go?

Which phenomenon generates electric current? A black body radiation B ultraviolet catastrophe C emission spectra D photoelectric effect