Which of the following is a good example of a contact force? A. Earth revolving around the Sun
B. a bridge suspended by cables
C. a ball falling downward a few seconds after being thrown upward
D. electrically charged hairs on your head repelling each other and standing up

A1500 w electric heater is plugged into the outlet of a 120 v circuit that has a 20 a circuit breaker. you plug an electric hair dryer into the same outlet. the hair dryer has power settings of 600 w, 900 w , 1200 w, and 1500 w. you start with the hair dryer on the 600 w setting and increase the power setting until the circuit breaker trips. under what setting does the circuit breaker trip.

If you held a stone over the mouth of a well and then let it go , what would happen to the stone? explain your answer.

Acar traveling at a constant speed of 22.0 m/s passes a trooper hidden behind a billboard. one second after the speeding car passes the billboard, the trooper sets off in chase with a constant acceleration of 3.50 m/s2. how long does it take the trooper to overtake the speeding car? solve this problem by a graphical method. on the same graph, plot position versus time for the car and the trooper.