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Let gEarth= 10 m/s2 throughout the exam I. You push on a 20 kg lawn mower that is in motion to the right, exerting a 100 N force on it that is directed 30° below the horizontal. There is a frictional force acting to the left, and the effective coefficient of kinetic friction between the grass and mower is 0.60. a) Draw a force diagram (to scale) for the lawn mower on the graph paper at right. Be sure to label forces. b) How much does the ground push up on the lawn mower? c) Find the acceleration of the lawn mower. d) While you are pushing the lawn mower it moves (circle one) to the right to the left and it is (circle one) speeding up Explain your choices: slowing down moving with a constant velocity 叩 J00p叫 鋼 p JOJ uqSSOIdXo vlou08 7 ηF触 ∝ ・ 7τ・C・ シl口 BI・ ε シ 『 SOHA,3v口耳コリSInsoJ o■lσ ドトHOЭ ・q ・uO■ OШ ■21n311Э pOods l配 Isuoo 8uunp uo■ 7Jo Let gEarth= 10 m/s2 throughout the exam tur1e,ru.ltr IIBq E-mZ V uollepr eql 1sel g't'? II. A ball of mass Mball traveling at a speed of vball swings at the end of a string. The string passes through a hollow tube and is attached at the other end to a hanging block. The slanted part of the string that swings in a circle makes an angle with the horizontal of θ, as shown. Assume that the hanging mass is at rest and stays at rest. 'lsluozlJortr eql qllAt oLEJo eltuu uu se{ulu prrB Euol ur-0s'0 q elc4c ? q Eurrrour sI tutll tu14s eql uud peluuls eql '{colq turtueq reqpIIB Jo ol ua\op aqru ,trollorl B qEnorql sassed luqt turRs ? Jo pue eqt te sEUIA\s s^u g?'Zpeads p Assume these are given quantities: Mball , vball ,θ a) Draw one force diagram for the ball, and one for the hanging block. Be sure to label all forces. unoJ uuvHЭ ・uO口ЮnpE uowodシ 10τ ◎ c) Find the mass of the hanging block in terms of the given quantities and any constants. d) If the mass of the ball is 200g, and it travels at a speed of 2.28 m/s, and the string makes an angle of 37° with the horizontal: i. how massive is the hanging block? ii. how big is the radius of the circular path? NOi■ 0■ 薔VInЭ u:● b) Apply Newton’s 2nd law to the ball, and then do the same for the block to get three DIFFERENT equations for the tension in terms of the given quantities, the radius and/or any other physical constants. Let gEarth= 10 m/s2 throughout the exam 3. A cart with wheels is placed on a horizontal table. A string tied to the cart passes over a pulley and is attached to a hanging weight as shown at right. The string pulls on the cart with a constant force, and friction and air resistance can be ignored. If the cart is released from rest, which choice below best describes its motion? 4. a) The cart moves with a constant speed. b) The cart quickly speeds up until it reaches a steady speed that depends on the size of the weight. c) The cart remains at rest unless the hanging weight is greater than the weight of the cart. d) The cart is always speeding up until it hits the pulley. e) The cart speeds up and then slows down as the hanging mass gets closer to the ground. The masses in the figure hang across a massless, frictionless pulley. What is the tension in the rope? a) 0.5 mg T b) mg c) 1.33 mg d) 2 mg m 2m e) 1.5 mg 5. Which of the following will remain in the air the MOST amount of time (neglecting air resistance)? a) A marble launched straight up from the ground at 18 m/s b) A marble launched from the ground with a speed of 20 m/s at an angle of 60° from the horizontal c) A marble that stays in the air for 3.0 s d) A marble that is dropped from 50 m above the ground e) A marble that is launched horizontally from a 50 m high TIPERS Let g = 10 m/s2 throughout the exam Earth B3.WWT98: ASTnONAUT NEAR n PUnET AND a Moon GnAVFATIoNAL Fonce At the instant shown, Catalina, an astronaut, is in space a planet Barolo. 2d from theCatalina, A moon of 6. Atdistance the instant show, an astronaut, is Barolo, in space a Aquitania, is a distance d onBorolo. the otherA side of Barolo. A distance 2d from the planet moon of Borolo, physics student trying to calculate the gravitational force on Aquitania, states: is a distance d on the other side of Barolo. At Catalina the moment shown, Catalina’s acceleration is: ― ― ― Catalina ― ― 翼 〔 "We onb need to worry about the planet Barolo, not its moon. ! Since ! Catalina is on the other side of Barolo, the ! !! ! !! gravitational field due to Aquitania is blocked by Barolo. The a) ! ! acting on Catalina is the gravitational force due to only force Barolo, !!!whichwe canfind using Newton's law of universal gravitation." b) Barolo Aquitania ― ― ― … … … … … … 0- 3計 L 2 !! ! What, if anythitg, is wrong with the student's statement? If nothing is wrong, state that explicitly, and then ! ! !!why !!! it is correct. explain c) If the statement is incorrect, state what is wrong and how you would correct it. !! d) You need to know what kind of motion Catalina is in to determine her acceleration. e) You need to know Catalina’s mass to determine her acceleration. 7. A 1-kg block and a 4-kg block are pushed across a table as shown. The blocks are speeding up. Which of the following statements is true about the amount of force exerted on the 4-kg block by the 1-kg block as compared to the force exerted on the 1-kg block by the 4-kg block? B3.CT99: ASTnONAUT NEAR A MOON-GRAvITATIoNAL Fonce is smaller. Ina)bothItcases shown at right, an astronaut is a distance x from a moon. The two cases are identical except that in Case A there is b) It is greater. large planet directly between the astronaut and the moon. 1 kg a case A ! 4 kg Planet two forces areon equal. gravitational Isc)the The force the astronaut by the moon (i) (iii)acceleration (ii) greater greater in A, Case in Cas€ B,oforthe the same in in order to answer this. d) We need to know the direction both cases? ― e) -11ト We need to know how hard the hand pushes in order to answer IElttllχ this. Explain your reasoning. Case B 8. The moon orbits the earth (RE=6380 km) every 27.3 days. The mean distance between ――Jnト 8 the center if the earth and the center the moon is 3.84 x 10 m. Which of the following is closest to the period of a satellite that is 800 km above the earth’s surface? 「 a) 1.6 hours b) 1.8 days c) 1.4 hours d) 1.7 hours e) 10.6 hours Copyright @ 2Ol5 Pearson Education, Inc. r42 三 二 三 llχ Moon ― ⑬