[ ] 10. A car misses a turn and drives straight off the edge of a flat cliff tha

Question

[ ] 10. A car misses a turn and drives straight off the edge of a flat cliff that is 45 m high. The police at the scene of the accident note that the point of impact is 120 m from the base of the cliff. How fast was the car traveling when it went over the cliff? A. 20 m/s B. 25 m/s C. 27 m/s D. 30 m/s E. 40 m/s [ ] 11. A stone is thrown horizontally from the top of a cliff while a second is dropped from rest from the same spot. Which motional variables are the same for the two stones throughout their motion to the ground? A. acceleration only B. acceleration and displacement C. acceleration, displacement and velocity D. none of the previous [ ] 12. A 0.6 kg model airplane flies in a horizontal circle on a guideline that is parallel to the ground. The smallest circle the plane can fly without breaking its guideline has a radius of 3.5 m. If you wish to use the same guideline when the model airplane is replaced by one with twice the weight that flies at the same speed what is the radius of the smallest circle now? A. 1.75 m B. 3.5 m C. 4.9 m D. 7.0 m E. none of the previous [ ] 13. A high diver weighing 700 N leaps from a 10 m tower. What is his gravitational potential energy at 4 m above the water's surface? A. 2,800 J B. 4,200 J C. 7,000 J D. 28,000 J E. 70,000 J [ ] 14. A carpenter is trying out hammers of different sizes. The heaviest hammer has a mass of 1.0 kg but is too heavy to swing rapidly. The carpenter finds that if he uses a 0.5 kg hammer, he can swing twice as fast. With which hammer can he generate more kinetic energy? A. same for both B. heavy one C. lighter one

Explanation / Answer

10) Using second equation of motion in vertical,

H = 0.5gt^2

t = sqrt(2H/g) = sqrt(2*45/9.8) = 3s

Speed v = s/t = 120/3 = 40 m/s

Option E is correct.

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