Mastering Physics: Practice Exam 3 for PHY121 Mechanics
School
Arizona State University**We aren't endorsed by this school
Course
PHY 121
Subject
Mathematics
Date
Dec 11, 2024
Pages
13
Uploaded by ProfessorMoon15900
Name _______________________ ASU ID#: _______________________ PHY121 (Jacobs) 2024 Fall: Exam 3 Practice (answer key at the end) On the real exam, you must agree to abide by the Test Rules as printed below-I am not allowed to work with anyone or anything (e.g., AI), or use any materials other than a calculator and writing utensil and whatever the instructor has explicitly allowed. -More specifically, I understand that use of any of the items below is strictly prohibited: oCell phone or smart watch oComputer or tablet oHeadphones or earbuds -I understand that receiving or helping to provide unauthorized aid is prohibited. -I agree not to discuss exam questions with any student who has not taken the exam. -I understand that violating any of the above may result in confiscation of my exam, an automatic failing exam grade and/or a referral to the Dean for further sanctions. Instructions Use the ANSWER SHEET to mark your multiple-choice answers, but you must show your work on the attached pages. You may separate this top sheet from the rest of the rest, but put it back on top when you hand it in. There are 18 questions on this practice exam, but on the real exam there will be 15 questions and the level of difficulty won’t be quite as high.
MECHANICS0ÃÃ?-xxa tx20012Ã?--xxxxta t*2202ÃÃ?-xxxaxx/+0netFFamm??Žpmv?m¸fNFFD??îEWF dr212Ã?Km?dEPdt?PF v22Ãw??carrt?¹rFttaŽ??netII2Ir dmmr?? Žî2iicmim xxm?ŽŽÃw?rw?¹?LrpI212KIw?0twwa?-20012ttqqwa?--a = acceleration E= energy F = force f = frequency h = height I = rotational inertia J = impulse K = kinetic energy k = spring constant= lengthL = angular momentumm = massP = powerp = momentumr = radius or distanceT = periodt = timeU = potential energyv= velocity or speedW = work done on a systemx= positionm= coefficient of frictionq= angle t= torque w= angular speed a= angular acceleration f= phase angle D? /sFkx*+212D?sUkxmaxcos(xxtwf?-+21Tfpw??2smTkp?2pTgp?122?GGm mFr12GGm mUr? /PHY121EQUATIONSGEOMETRY AND TRIGONOMETRY Rectangle A?bhTriangle A?12bhCircle A?pr2?2pCr?srqRectangular Solid ?VwhCylinder ?pVr2Sr?-22pp2rSphere 34?3pVr?4pSr2Right Triangle ab22-?c2sinq?acbccosq?tanabq?A = area C = circumference V = volume S = surface area b = base h = height = lengthw = widthr = radiuss= arc lengthq= anglecab90°qs r qPHYSICAL CONSTANTS A B?ABcosqAB¹?ABsinqG6.67?¹10/11N[m2*+Universal gravitational constant,Acceleration due to gravityat Earth’s surface,g?9.8 mSpeed of light, c3.00?¹108m/skg22/s||
Rotational Physics 1.On a compact disc (CD), digital bits of information are encoded sequentially along an outward spiraling path for which, at any given point, as a radius ࠵?. To read the digital information, a CD player rotates the CD so that the player’s readout laser scans along the spiral’s sequence of bits at a constant linear speed of 1.25 m/s. Thus, the player must accurately adjust the rotational frequency of the CD as the laser moves outward. If ࠵? = 5.0 cm, what is the value of this rotational frequency? a.400rpm b.240rpm c.60rpm d.25rpm e.1500rpm 2.A thin rod with uniform density has mass ࠵?and length ࠵?, and is rotated around an axis that is inside the rod. That axis is at a distance࠵?/10from one end and is oriented perpendicular to the rod. What is the moment of inertia of the rod about that axis? For reference, the moment of inertia of such a rod about a perpendicular axis through its center is ࠵?!"=##$࠵?࠵?$, whereas the moment of inertia of such a rod about an end would be ࠵? =#%࠵?࠵?$. a.!!"࠵?࠵?#b.!$"࠵?࠵?#c.%!!&"࠵?࠵?#d.’#($"""࠵?࠵?#e.)$$""࠵?࠵?#
3.A wheel of radius 0.5 m rolls without sliding on a horizontal surface as shown. Starting from rest, the wheel moves with constant angular acceleration 6rad/s$. The distance traveled by the center of the wheel in the first 3 seconds is roughly a.27 mb.14 mc.6.8 md.3.4 me.0.0 m4.A round object of mass ࠵?and radius ࠵?has a non-unform density, making its moment of inertia equal to ࠵?࠵?࠵?$, where ࠵?is dimensionless number. Suppose this round object was rolling freely on flat ground with translational speed ࠵?&when it began to roll down a hill. At the bottom of the hill the object had translational speed ࠵?’. How much higher is the top of the hill compared to the bottom of the hill? a.(!")(#"$*b.(1 + ࠵?)(!")(#"$*c.(1 − ࠵?)(!")(#"$*d.(1 + 2࠵?)(!")(#"$*e.>1 +#+?(!")(#"$*
5.The forearm shown in the figure accelerates a 3.6-kg ball at 7.0 m/s$by means of the triceps muscle, as shown. What is the force that must be exerted by the triceps muscle? (Hint: first compute the torqueneeded to accelerate the ball.) a.310 N b.1000 N c.160 N d.620 N e.200 N 6.The L-shaped object shown in the figure consists of three small masses connected by extremely light rods. Assume that the masses shown are accurate to three significant figures. How much work must be done to accelerate the object from rest to an angular speed of 3.25 rad/s about the x-axis? a.34.2 J b.173 J c.53.1 J d.10.5 J e.17.1 J
A block of mass m = 4.0 kg is hung from a light string that is wrapped around a frictionless pulley having the shape of a solid cylinder whose radius is 12 cm. Use this scenario for the next two problems.7.If the block is currently falling downward at speed of 3.0 m/s, what is the angular speed of the pulley? a.0.25 rad/s b.4.0 rad/s c.25 rad/s d.160 rad/s e.39 rad/s 8.If the block accelerates downward at rate of *$when it is released, what is the mass M of the pulley? a.2.0 kg b.4.0 kg c.6.0 kg d.8.0 kg e.10 kg
I was listening to some music with my record turning at a constant 42 rpm when my dog, Burger, accidentally ran into the power cord, turning the player off. The record slowed to rest at a uniform rate due to the frictional torque inside the player. The disk-shaped record has a mass of 150 g and a radius of 15 cm and it took 10 seconds to come to rest. Use this for the next two problems. 9.What must be the torque provided by the record player to keep it spinning at its operational rate? a.7.4 × 10),N ⋅ mb.7.4 × 10)%N ⋅ mc.7.4 × 10)$N ⋅ md.7.0 × 10)%N ⋅ me.7.0 × 10)$N ⋅ m10.After Burger unplugged the record player and the record stopped, how much mechanical energy was lost? a.4.13 × 10),J b.4.13 × 10)%J c.4.13 × 10)$J d.1.4J e.1.6 × 10)$J
Misty Copeland spins initially at 1.5 rad/s with her arms and one leg extended. When she draws her arms and legs in toward her body her moment of inertia becomes 0.90 kg ⋅ m$and her angular speed increases to 4.5 rad/s. Use this for the next two problems. 11.What must have been Misty’s initial moment of inertia? a.0.10 kg ⋅ m$b.0.30 kg ⋅ m$c.0.60 kg ⋅ m$d.2.7 kg ⋅ m$e.8.1 kg ⋅ m$12.How much work did Misty have to do in the previous problem to alter her motion that way? a.910 J b.610 J c.3.0 J d.9.1 J e.6.1 J
Static Equilibrium A store sign has uniform density, a mass of ࠵?and length ࠵?. It is supported by a small loose bolt attached to the wall at one end and by a wire at the other end, as shown in the figure. In this problem you may use ࠵? = 20 kg, ࠵? = 3.0 m, and ࠵? = 25∘. Use this for the next two problems 13.What is the tension in the wire? a.200 N b.400 N c.230 N d.100 N e.50 N 14.How much vertical force does the wall provide? a.98 N b.196 N c.49 N d.245 N e.490 N
Momentum and Collisions 15.A tennis ball of mass m rebounds from a racquet with the same speed ࠵?as it had initially. as shown above. The magnitude of the momentum change of the ball is a.0b.࠵?࠵?c.2࠵?࠵?d.2࠵?࠵? sin ࠵?e.2࠵?࠵? cos ࠵?16.A 2.0-kg ball traveling at 3.0 m/s hits a vertical wall and rebounds with the same speed. If the contact time with the wall is 1.0 × 10)$s, the magnitude of the force exerted on the ball is most nearly a.6.0 N b.12 N c.300 N d.600 N e.1,200 N
17.A block of mass m = 3.0 kg, moving on a frictionless surface with a speed ࠵?.=9.0 m/s, makes a sudden perfectly elastic collision with a stationary block of mass M. Just after the collision, the 3.0-kg block recoils (backward) with a speed of |࠵?’| = 3.0/0. What is the speed ࠵?of the other block? a.6.0 m/s b.8.0 m/s c.9.0 m/s d.10 m/s e.12 m/s Simple Harmonic Motion 18.A 0.50-kg block slides along a horizontal frictionless surface at 2.0 m/s. It is brought to rest by compressing a very long spring of spring constant 800 N/m. The time between impact of the block with the spring and when the spring is maximally compressed is: a.0.025 s b.0.16 s c.0.039 s d.0.079 s e.0.0063 s
Answer Key 1.b 2.e 3.b 4.b 5.a 6.a 7.c 8.d 9.a 10.e 11.d 12.e 13.c 14.a 15.e 16.e 17.a 18.c