Static and Kinetic Friction - Introductory Physics - Solved Paper, Exams of Physics

Download Static and Kinetic Friction - Introductory Physics - Solved Paper and more Exams Physics in PDF only on Docsity! 3. (20 pts) A block of weight, W = 50.N, is in contact with a vertical wall at a height, H = 4m, above the ground. The coefficients of static and kinetic friction between the block and the wall are 4, = .4 and UW, = .2 respectively. You apply a force F = 2W at 0 = 45° as shown. FE 777 a) Find the direction of the friction force between the block and the wall. Justify your answer. b) How high is the block above the ground after lime, t = 2 sec. Justify your answer. [a = 8 pts, b = 12 pts] y &) tit re fnvctien F Shy tr may < Ff. mG, Hyse me ton sf 4, “oy, em ik 5 diatse Lo tenn po M e Fy -VUi~ Fp 2G Me Fy = UWCOST fp hyo Me 6e W 2 Qw sinh s™ maveg x (2 a \w ew 2 The Ss jd clad re To. f (o~ yece dyery tf. \olack fe Le dation es / Meo check } f th, ) Z ie : Nee ef exceeds F f pax Fp € Ms NM (ww) £ Cv)ORw) 22 Caywy) Else w) Ves, the fo ck se 6 Leh de Ihevery, 5. (4 pts each) Write letter of correct answer in box. Le. awa c ve Il. ders yecters yeedes vel. veel chance EMPTY BOX GETS ZERO POINTS!!!! Which of the following scenarios could have the acceleration vs time graph shown above. a) Ball thrown up, stops at the top and begins to fall. b) Car slowing down from 50 mph to 20 mph, then speeding up to 40 mph. c) Ball on a rope swinging in a vertical loop from the bottom to the top. d) Car driving forward, slowing down to a stop, then backing up in reverse. e) Both a) and d) For a car driving around a circular track (radius R = 500 m) at a constant 50 km/hr, the car has a) constant position and changing velocity. b) changing velocity and constant acceleration. ©) changing position and changing acceleration. d) constant velocity and changing acceleration. a would bo Che v \ <} Come ace! wey decreeke IAN mes), be d f a Never heve Qrte 3 loc Chur din, of ve ( gd eccel cheage. pets ties ea obveehye cheeses HI. A large truck runs into the back of a small car that is stopped at a stop sign. Which of the following statements is true? v a) The magnitude of the force on the truck is bigger. f 4eack Fer b} The magnitude of the force on the car is bigger. c) The magnitude of the acceleration of the truck is bigger. m,4r ° Mm, A, }The magnitude of the acceleration of the car is bigger. + €) Both a) and c) because F=ma a = We Qa f) Both b) and d) because F=ma AT Ay ¢ tee <i] IV. A plane flys in a horizontal circle of radius R = 1000 m at a constant 300 Cc. km/hr. The force on the plane due to the air is a) in the same direction as the weight of the plane. b) in the opposite direction as the weight of the plane. larger in magnitude than the weight of the plane. d) equal in magnitude to the weight of the plane. c) smaller in magnitude than the weight of the plane. fa \C Ves 2 component EF, : co c u a> Fit Fae wy ap Fy r = Vv. Block m, is on top of block m,. The blocks have an initial velocity, v, as shown. There is friction between the blocks and also between m, and the Cn ground. The blocks stay together and come to rest after travelling for a given time, t. 1 a —_____-» a> ‘ v t Which is true? There is a stalic friction force that slows block 1 down even though it is nee moving. PrK AG by There are two friction forces on block 2, both’of:them-direeted to-the left. ~ iv ff ey AX The coefficient of kinetic friction between block 2 and the ground is 1, = vi(2gt) _&) The coefficient of static friction between block 1 and block 2 is p, = w/(gt) S) More than one of the above is true. =| {” ‘ nF “ tT” fe - dd F Static Ain do fap w sla #1 dows 9 .