PES Physics 1 Practice Questions Exam 2. Name: Score: /...

Transcription

1 Practice Questions Exam /page PES Physics Practice Questions Exam Name: Score: /... Instructions Time allowed for this is exam is hour 5 minutes... multiple choice (... points)... written problems (... points) For written problems: Write all answers in the spaces provided. Answers to questions involving calculations should be evaluated to three significant figures and given in decimal form. Despite an incorrect final result, credit may be obtained for method and working, provided these are clearly and legibly set out. Only required equipment may be placed on the desk. No talking permitted. No questions. If you are unsure of what is being asked, take your best guess and state your reasoning. Cell phones must be turned off. Equipment This Question/Answer booklet Pens, pencil, eraser, ruler, water bottle Scientific calculator (cell phones may not be used as a calculator)

2 Practice Questions Exam /page Information you may need for this exam f = µ s F n ( ) ˆ ( ) ˆ ( ) ˆ s,max f k = µ k F n v= rω v Fcentripetal= m v = ω r R D= v CρAv mg CρA A B= A B B A i+ A B B A j+ A B B A k a rad = ter min al a tan W = F d y z y z z x z x x y x y = ω r = α r I= miri i = mv dw P= dt Klin Uel U g = mgy Krot com = Iω I = I Mh = ks Quadratic formula: if K i + U i + W other = K f +U f J = F t= p avg xcom = xidmi M i p = mv P= P i f dθ ω ( t) = dt dω α ( t) = dt ω(t) = ω + α t 0 θ ( t) = θ0+ ω0t+ α t ω = ω + αθ θ ( ) 0 0 θ ( t) = θ0+ ωt α t θ ( t) = θ0+ ( ω0+ ω ) t ax +bx+c=0 ; ± x= b b 4ac a

3 Practice Questions Exam /page3 Multiple Choice Problems: Circle the correct answer ) Two objects with different masses collide and stick to each other. Compared to before the collision, the system of two objects after the collision has a) the same total momentum and the same total kinetic energy. b) the same total momentum but less total kinetic energy. c) less total momentum but the same total kinetic energy. d) less total momentum and less total kinetic energy. e) not enough information given to decide ) DVD is rotating with an ever-increasing speed. How do the centripetal acceleration a rad and tangential acceleration a tan compare at points P and Q? a) P and Q have the same a rad and a tan. b) Q has a greater a rad and a greater a tan than P. c) Q has a smaller a rad and a greater a tan than P. d) P and Q have the same a rad, but Q has a greater a tan than P. 3) An elevator is being lifted at a constant speed by a steel cable attached to an electric motor. Which statement is correct? a) The cable does positive work on the elevator, and the elevator does positive work on the cable. b) The cable does positive work on the elevator, and the elevator does negative work on the cable. c) The cable does negative work on the elevator, and the elevator does positive work on the cable. d) The cable does negative work on the elevator, and the elevator does negative work on the cable.

4 Practice Questions Exam /page4 4) Two iceboats (one of mass m, one of mass m) hold a race on a frictionless, horizontal, frozen lake. Both iceboats start at rest, and the wind exerts the same constant force on both iceboats. Which iceboat crosses the finish line with more kinetic energy (KE)? a) the iceboat of mass m: it has twice as much KE as the other b) the iceboat of mass m: it has 4 times as much KE as the other c) the iceboat of mass m: it has twice as much KE as the other d) the iceboat of mass m: it has 4 times as much KE as the other e) they both cross the finish line with the same kinetic energy 5) When two bodies of different masses collide, the impulses they exert on each other are: a) equal for all collisions b) equal but opposite for all collisions c) equal but opposite only for elastic collisions d) equal but opposite only for inelastic collisions e) equal but opposite only when the bodies have equal but opposite accelerations 6) A wheel is rotated counterclockwise as shown. What direction it its angular velocity? a) Into the board,. b) Out of the board,. c) To the right. d) To the left. 7) For the rectangular stick shown, the moment of inertia for rotation about the center is I j, the moment of inertia for rotation about the point /4 of the length is I k, and the moment of inertia for rotation about the end is I l. Which of the following is the correct listing of moments of inertia from largest to smallest? a) I j, Ik, I l b) I, I, I c) Il, I j, I k d) I, I, I e) I j= Ik= Il j l k l k j

5 Practice Questions Exam /page5 Written Problems: ) A car with mass 850 kg is travelling at 60 km/h. The coefficient of friction is (a) What is the change in kinetic energy when the car brakes and comes to a stop? (b) What is the stopping distance of the car? [Hint: work done by a constant force must be equal to the energy found in part (a).] ) A boy rides a sled down an icy (and therefore frictionless) hill whose height above the ground is given by the equation y = x 3/, where y is in meters when x is in meters. If he starts from rest at x = 3.5m, how fast will he be going at the bottom? 3) An 800 kg car is traveling north at 8.0 m/s when it is hit side-on by a 300 kg stolen truck traveling east at 8.0m/s. The two become joined during the collision. What is their final velocity? 4) A rubber mallet consists of a 5.00 cm long rubber block with a mass of g placed at the end of a 0.0 cm long wooden handle with a mass of 00.0 g. Let the left end of the handle be the position x = 0. (a) (b) At what x position are the centers of mass of the: (i) wooden handle? (ii) rubber block? Where is the centre of mass of the mallet? 0.0 cm 5.00 cm

6 Practice Questions Exam /page6 5) The -kg physical-pendulum with moment of inertia 5.5 kg m and center of mass at G is released from rest at θ = 65º. How fast will it be going when it swings through the vertical (θ = 90º)? 6) A roller coaster starts from rest at point A where the height h = 5m. It slides along the track without friction. a) What is the velocity at point B? b) What is the centripetal acceleration at point B? The radius of the loop-to-loop s circle is 7.5m. c) What is the normal force acting on a 75 kg rider of the roller coaster at the top of the loop-to-loop (point B)? 7) A record rotates at a constant 33 rev/min. What is the angular displacement during 5 seconds? (Express your answer in both radians and degrees.)

7 Practice Questions Exam /page7 8) One day finds your instructor needing to lift a 0.0 kg box. As usual, he has completely over-complicated the procedure by using a massless pulley and a motor as shown below. Your instructor observes that when the motor has lifted the box 4.0 m above the floor, it has a speed of 5.0 m/s. a) How much gravitational potential energy does the box have? (Assume the on the floor, the box had zero potential energy.) b) How much kinetic energy does the box have? c) Assuming the box started from rest, how much work was done by the motor lifting the box to 4m? 9) Two particles, each with mass m = 0.85 kg, are fastened to each other, and to a rotation axis at O, by two thin massless rods, each with length d = 5.6 cm. The combination rotates around the rotation axis with the angular speed ω = 0.30 rad/s. Measured about O, what are the combination s (a) rotational inertia and (b) kinetic energy? 0) Make sure you know how to solve and understand the physics of relevant HW and in-class problems!