Rolling Coaster Motor - Introductory Physics - Solved Paper, Exams of Physics

Download Rolling Coaster Motor - Introductory Physics - Solved Paper and more Exams Physics in PDF only on Docsity! Phuatc yes Ba, University of Califc Fault = . Devartmaent BA! 2002 Widterm 2 Physics 8A, J4atonsen Second Midter..., .cuwii 2 April 13, 1999 12:30PM You will be given 80 minutes to work this exam. No books are allowed, but you may use a handwritten note sheet no larger than an 8 1/2 by 11 sheet of paper. Your description of the physics involved in a problem is worth significantly more than any numerical answer. Show all work, and take particular care to explain what you are doing, Please use the symbols described in the problems, tell us why you're writing any new equations, and label any drawings that you make. Write your answers directly on the exam, and if you have to use the back of a sheet make sure to puta note on the front. Do not use a blue book or scratch paper. v= dx/dt a=dv/dt X(t) = Xytvyttl/Qar” S Fema F.=mvsr F,=u,N W = Fx P= dWidt K=12mVv U=mgh AK =K,K, AU=U-U, W=AU+AK+AE,,+AE, h 5 c DISCUSSION aru oy - _. eur: Wen pyelep?  1) (20 points) Roller coaster motor (power) The motor on a roller coaster pulls a car of mass M to the top of the first hill at a constant velocity V. The hill is D meters long, and is at an angle @ (see sketch). a) During the lift, what is the power provided by the motor? b) During the lift, what is the force provided by the motor? pope 7 4) (20 points) Frictional braking wy yet An object of mass M, is moving to the left with speed s, past the point x=0 when it suddenly collides with an object of mass M, moving at speed s,, (See illustration). Note that s, and s, are speeds, hence are positive numbers, but one object is moving to the left and one to the right. After the collision they stick together. a) In terms of M,,M,,s, and 5, determine whether they will move to the left or the right after the collision b) After the collision, they move together with a coeiticient of kinetic friction 1, between the blocks and the surface... How far do they move before stopping? Mos g, te m5, a “ 4a ' t on (i ys ol Oe LE - Wir Sp i A “F Denn edie: No Oto = (rae) a Ah } N= (Mame) 4 Ly ke peer ee get 7  5) (10 points) The Scale A professor is standing on a “scale” in an elevator. The scale measures the force exerted on the floor by the professor. Itreads 1000 Newtons when the elevator is stationary (assume g=10 m/s"), What does it read if the elevator is accelerating upward at 20m/s*? ~~ - i \ gs jops = m (1078) forebo- 7  6) (2 points each) Miscellanous 1) Of the following simations, which one is impossible? a) a body having velocity east and acceleration east b) a body having velocity east and acceleration west ¢) a body having zero velocity and non-zero acceleration d) a body having constant acceleration and variable velocity fey a body having constant velocity and variable acceleration 6.2) A particle moves at a constant speed in a circular path. The instantancous velocity and instantaneous acceleration vectors are: 2 % a) both tangent to the circular path 02 ns b) both perpendicular to the circular path | iw? ¢) perpendicular to each other \ Ll d) opposite to each other \ / e)’ none of the above “ 6.3) A “newton” is the force a) of gravity ona 1 kg body b) of gravity on a 1 gram body ec) that gives a 1 gram body an acceleration of 1 cm/s? “d)) that gives a 1 kilogram body an acceleration of 1 m/s’ C) that gives a | kilogram body an acceleration of 9.8 m/s* 6.4) In a tug-of-war, two students each pull on the rope with 100 Newton forces, in opposite directions, The tension in the rope is a) zero ' b) 50 Newton N c) 100 Newton <— a d) 141 Newton é€) 200 Newton 6.5) A heavy steel ball B is suspended by a cord from a block of wood W. The entire system 1s dropped through the air. Neglecting air resistance, the tension in the cord while falling is: a) zero b) the difference in the masses of B and W ce) the difference in the weights of Band W d) the weight of B e) none of these Tae me pee 7d 7