P211 MT2 Fall 2004 Form A 1 A student wants to determine the coefficients of static friction and kinetic friction between a box and a plank She places the box on the plank and gradually raises one end of the plank When the angle of inclination with the horizontal reaches 27 5 the box starts to slip and slides down the plank in 4 1 s The coefficient of static friction is A B C D E 0 425 0 462 0 479 0 521 0 887 2 A trunk with a weight of 250 N rests on the floor The coefficient of static friction between the trunk and the floor is 0 42 while the coefficient of kinetic friction is 0 20 If the trunk is pushed with the minimum force required to start the trunk moving and continues to be pushed with this force how far will the trunk have moved after 5 s A B C D E 35 6 25 7 m 2 5 m 24 5 m 2 75 m 27 m 3 A small block of mass M is released at rest from the inner edge of a frictionless stationary semicircular bowl and slides down What can you say about the normal force N 1 on the block just after it is released and the normal force N2 on the block when it is at its lowest point N1 N2 A B C D E 35 4 N 1 Mg and N 1 Mg and N 1 Mg and N 1 Mg and N 1 Mg and N 2 Mg N 2 Mg N 2 Mg N 2 Mg N 2 Mg Page 1 37 17 P211 MT2 Fall 2004 Form A 4 At time t 0 a 2 kg particle has a velocity of 4 m s i 3 m s j Att 3s its velocity is 2 m s i 3 m s j During this time the total work done on it was 43 4 A B C D 40 J 12 J 4 J 4J E 4J i 36 J j 5 A woman lifts a barbell 2 0 m in 5 0 s If she lifts it the same distance in 10 s the work done by her is A B C D E one fourth as great one half as great the same two times as great four times as great 6 A 100 kg hockey player skates at 2 5 m s toward a railing at the edge of the ice and then stops himself by grasping the railing with his outstretched arms During the stopping process his center of mass moves 40 cm toward the railing What average force must he exert on the railing A B C D E 40 10 7 8 N 15 6 N 781 N 1562 N 3125 N 7 A Physics 211 student watches a maple leaf gently fall from a tree on a calm autumn day The leaf is falling at constant speed and she draws the following conclusions Which if any are TRUE i The net force on the leaf is zero ii The work done by air resistance has the same magnitude as the work done by gravity iii The mechanical energy K U is a constant during the fall of the leaf iv The work done by air resistance on the leaf is negative A B C D E 40 12 iii and iv only i and ii only i ii and iv only i ii and iii only all four statements are true Page 2 47 8 P211 MT2 Fall 2004 Form A 8 A large block of cheese attached securely to a bungee cord is released from rest from a stationary helicopter 48 4 The helicopter is 50 meters above the ground The bungee cord has an unstretched length of 20 meters and a spring constant of 50 Newtons per meter The mass of the cheese is 100 kg Unfortunately the helicopter is too low and the cheese hits the ground With approximately what velocity does it hit the ground A B C D E 0 m s 16 m s 24 m s 32 m s 50 m s 9 An object of mass m slides without rolling down the frictionless fun slide depicted in the figure If the object begins sliding from rest at the top of slide what is the ratio of the speed of the object at B to the speed of the object at A 48 16 A 2 to 1 B 2 to 1 C 3 to 2 D 3 to 2 E 3 to 4 10 A 1 kg ball is loaded into a spring gun with a spring constant of 105 kg s2 If the spring is compressed by 10 cm and the ball is shot up vertically how high does it rise into the air A B C D E 12 7 cm 1 3 m 12 7 m 102 0 m 51 0 m Page 3 48 19 P211 MT2 Fall 2004 Form A 11 The first graph below shows the potential energy U x for a particle moving along the x axis Which of the following five graphs correctly gives the force F x exerted on the particle A B C D E I II III IV V 12 A 25 kg bear slides from rest 8m down a lodgepole pine tree moving with a speed of 5 7 m s just before hitting the ground What is the average frictional force that acts on the bear A B C D E 51 2 0N 195 N 780 N 1550 N 2450 N 13 Superman mass 78 0 kg stops a train mass 18619 kg headed for a broken bridge The train was initially traveling at 60 0 km h During the constant deceleration the passengers experience an average horizontal force of 0 410 their own weight How long does it take for the train to come to a stop A B C D E 49 3 14 93 s 6 12 s 1 70 s 57 55 s 4 15 s Page 4 61 12 P211 MT2 Fall 2004 Form A 14 A 2 kg particle traveling with a speed of 2 5 m s as shown is acted on by a force that changes its velocity The 61 5 final velocity is 1 m s in the opposite direction If v is to the right what is the impulse given to the block in kg m s 2 5 m s before A B C D E 1 m s after 5 0 7 0 3 0 7 0 15 Daniella and ChiChi stand on a frictionless cart on one side of the room while Austin stands on a second frictionless cart on the opposite side of the room Both carts are initially at rest and a long rope is strewn between them The girls pull as hard as they can on the rope while Austin merely holds on to his end A short while later the carts collide Which of the following must be true 57 11 A Austin s …