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| Suppose you dropped a rock from a bridge into a valley below. Earth pulls on the rock and it accelerates downward. According to Newton's third law, the rock must also be pulling on Earth, yet we don't notice the Earth accelerating upward. Explain. | ??? |
| Why does a package on the seat of a bus slide backward when the bus accelerates quickly from rest? Why does it slide forward when the driver applies the brakes? | ??? |
| Your new motorcycle weighs 2450 N. What is its mass in kilograms? | ??? |
| You place a 7.50-kg television set on a spring scale. If the scale reads 78.4 N, what is the acceleration of gravity at that location? | ??? |
| An artillery shell has a mass of 55 kg. The shell is fired from a gun, leaving the barrel with a velocity of 770 m/s. The gun barrel is 1.5 m long. Assume that the force, and thus the acceleration, of the shell is constant while the shell is in the gun barrel. What is the force on the shell while it is in the gun barrel? | ??? |
| A 140-g baseball traveling 45.0 m/s strikes the catcher's mitt, which, in bringing the ball to rest, recoils backward 11.0 cm. What was the average force applied by the ball on the glove? | ??? |
| A person has a resonable chance of surviving an automobile crash if the deceleration is no more than 30 g's. Calculate the force on a 70-kg person accelerating at this rate. | ??? |
