Sample Exam III
Visit the site on Sunday for answers and perhaps solutions(?).1) You want to build a ski lift for a small hill resort. The hill is sloped at 200to the horizontal and a 100 kg skier is to be pulled along the sloping side of the hill through a distance of 50m. The skierıs speed is 0 m/s at the bottom and 6.0 m/s at the top. If µk is 0.05, what is the tension needed in the cable pulling the skier? ( Answer: 417 N.)
Solution: 2) A bullet of 10 g mass moving horizontally with a velocity of 505 m/s hits a wooden block of 10 kg mass sitting on a horizontal table and gets embedded inside the block. After the collision the block moves through a distance of 10 m on the table before coming to rest. Compute the µk of the surface and the block
.: Solution The answer is 0.001 and not 0.01 and all except the last number are correct.
3) A 12 kg bomb is projected upwards with an initial Vy = 9.8 m/s. At the highest point it breaks up into two pieces with mass ratio of 1:2. The larger fragment falls downwards with a velocity of 9.8 m/s. Find total vertical distance traveled by the smaller piece form the launching point of the bomb.( Answer: 24.5 m.) Solution for 3 and 4. 4) A lumberjack of mass of 100 kg is at rest at one end of 10 ft log of mass 200 kg which is also at rest relative to the shore. Now he runs to the other end of the log reaching velocity of 6 m/s relative to the shore at the very end of the log in 10 seconds and then jumps upon an identical log at rest with respect to the shore. Assume that logs move without friction on water. What is the velocity of each of the logs with respect to the shore after he lands on the second one? (Answer: vel of the first log -3 m/s and the second one 2 m/s.) Solution for 3 and 4.5) An elevator car of mass 800 kg with zero initial downward velocity falls from a height of 5 m, hits a buffer spring and compresses it by 0.7 m before coming to rest. What is the force constant of the spring? Was done in class. 6) Chap 6 Sec 5. Circular Motion - Centripetal Acceleration. 7) Home work assignments and Class examples and Activity computations.Go to additional Problems( Should be available after 4:00 P.M. on Friday)