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Unformatted text preview: Your Name. Student ID#. 1Ba Physics for Scientists and Engineers: Oscillations, Waves, Electric- ity and Magnetism Midterm #1. Friday 18th April. Instructor: Steve Cowley Please do not write in this region Question 1. Question 2. Total. Open book, open notes – no talking. Please write your answers in the space provided below. Partial credit is given for answers that are on the right track so show your working. You may use rough paper but please put the working on these sheets. Answers need not be more accurate than two significant figures. If you don’t have much time you will get almost all of the credit for writing down the right expression (with the right numbers inserted) and leaving the arithmetic undone. You may take π = 3 . 14 or even just 3.. No calculators or cell phones are to be used in the exam . Question 1. Cartoon Hitchhiking – the Death Wish. 20 points You are desperate to get home quickly on your bicycle and decide to hitch yourself to a passing truck that has velocity 20 ms- 1 . You have a spring of negligible unstretched length spring constant k = 2 Nm- 1 and you weigh M = 72 kg . Assume the spring can be stretched to any length. When the truck passes you sitting stationary on your bicycle, you attach the spring to the truck and you are pulled forward alongside the truck. Initially you move slower than the truck and the spring stretches – subsequently you are accelerated until you begin to over take the truck. You perform oscillations about the moving truck. Ignore the (very real) possibility that you hit the truck during these oscillations and the drag (until part (e)). (a) Calculate the period of your oscillation. 4 points ω = r k M = 1 6 s- 1 → T = 2 π ω = 12 π ∼ 38 s (b) What is your velocity (relative to the ground) when you pass the truck? Hint. Consider your motion inHint....
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- Spring '07
- Magnetism, Truck, maximum displacement