PHYS 102 CHAPTER 3 HOMEWORK
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Which has the larger linear momentum: a 2,100kg houseboat going 8 m/s or a 770kg speedboat going 25 m/s? A 7,800kg truck runs into the rear of a 1,000kg car that was stationary. The truck and car are locked together after the collision and move with speed 4 m/s. What was the speed of the truck before the collision? In compressing the spring in a toy dart gun, 0.6 J of work is done. When the gun is fired, the spring gives its potential energy to a dart with a mass of 0.09 kg. At NASA's Zero Gravity Research Facility in Cleveland, Ohio, experimental payloads fall freely from rest in an evacuated vertical shaft through a distance of 132 m A bicycle and rider going 12 m/s approach a hill. Their total mass is 71 kg. A 1,000W motor powers a hoist used to lift cars at a service station. A running back with a mass of 98 kg and a velocity of 7 m/s (toward the right) collides with, and is held by, a 147kg defensive tackle going in the opposite direction (toward the left). What is the velocity of the tackle before the collision for their velocity afterward to be zero? (Remember, velocity is a vector) An elevator is able to raise 9,800 N to a height of 37 m in 14 s. It takes 120 minutes for a middleaged physics professor to ride his bicycle up the road to Alpe d'Huez in France. The vertical height of the climb is 1,120 m, and the combined mass of the rider and bicycle is 81 kg. What is the bicyclist's average power output? When you throw a ball, the work you do to accelerate it equals the kinetic energy the ball gains. If you do twice as much work when throwing the ball, does it
go twice as fast? Explain. Describe the motion of an object that possesses kinetic energy yet undergoes no net displacement. If we know that a force of 5 N acts on an object while it moves 2 meters, can we calculate how much work was done with no other information? Explain your answer During a headon collision between two automobiles, the occupants are decelerated rapidly. Use the idea of work to explain why an air bag that quickly inflates in front of an occupant reduces the likelihood of injury. (Select all that apply.) If you hold a ball at eye level and drop it, it will bounce back, but not to its original height. Identify the energy conversions that take place during the process, and explain why the ball does not reach its original release level.