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Unformatted text preview: nichols (scn285) Homework #8 Erskine (58200) 1 This print-out should have 24 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points A force acting on a body in empty space increases at a constant rate from zero. The body has a mass of 10 kg, and after 4 seconds the force is 50 N. What is the speed of the object at 4 sec- onds? 1. 1 m/s 2. 10 m/s 3. 4 m/s 4. 25 m/s 5. 100 m/s 6. 40 m/s 7. 50 m/s 8. 500 m/s 002 (part 1 of 2) 10.0 points A(n) 12200 lb railroad car traveling at 6 . 2 ft / s couples with a stationary car of 6480 lb. The acceleration of gravity is 32 ft / s 2 . What is their velocity after the collision? Answer in units of ft / s. 003 (part 2 of 2) 10.0 points What impulse did the first car receive? Answer in units of lb s. 004 10.0 points A(n) 78 kg man, standing erect, steps off a 2 . 7 m high diving platform and begins to fall from rest. The man comes to rest 1 . 5 s after reaching the water. The acceleration of gravity is 9 . 8 m / s 2 . What average force did the water exert on him? Answer in units of N. 005 (part 1 of 2) 10.0 points A(n) 6200 kg rocket traveling at 3400 m / s is moving freely through space on a journey to the moon. The ground controllers find that the rocket has drifted off course and that it must change direction by 9 . 3 if it is to hit the moon. By radio control, the rockets engines are fired instantaneously ( i.e., as a single pel- let) in a direction perpendicular to that of the rockets motion. The gases are expelled ( i.e., the pellet) at a speed of 4500 m / s (relative to the rocket). What mass of gas must be expelled to make the needed course correction?...
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