Practice Test #3 (Exam 2)
Supplemental Instruction
Iowa State University / Leader: / Wesley Hutter
Course: / PHYS 221
Instructor: / Canfield/Herrera-Siklody
Date: / 11/04/2013

Print this test off and bring it with you to the SI exam review on Monday, November 3rd.

  1. A spring that has k = 1.00 * 104 N/m provides a roller coaster of m = 1.00 * 103 kg an initial velocity as it slides along a track without friction. The track includes two loop-the-loops, the first one with radius R1 = 100.0 m, and the second with radius R2 = 50.0 m. What is the minimum distance the spring needs to be compressed from equilibrium to ensure that the roller coaster does not fall off the tracks at any point during the ride?
  1. 9.90 m
  2. 14.0 m
  3. 15.7 m
  4. 22.1 m
  5. 88.0 m
  6. Who cares? I’m on a freaking roller coaster!
  1. The energy diagram here depicts an object of mass m = 1.0 kg that is subject to a one-dimensional force that varies with respect to the location at which the object is found. It is the only force acting on the object. When the object is placed at x = 6.0 m, its velocity is approximately 6.3 m/s to the right. What is the maximum kinetic energy the particle will achieve?

  1. 10 J
  2. 20 J
  3. 30 J
  4. 40 J
  5. 50 J
  6. A lot.
  1. Two puppies, Jobin (mass J) of mass 5.0 kg, and Fluffy (mass F) of mass 6.0 kg run towards a toy at the middle of a room perpendicular to each other. They both reach the toy at the same time, but due to their underdeveloped motor skills, they collide and wrestle with each other instead. While entwined with each other, they slide along the floor at a 45 degree angle to both of their initial motions, and come to a stop due to friction after about 1.0 m. The coefficient of kinetic friction between the puppies and the floor is about 0.30. What was the speed of Jobin just before the collision?
  1. 1.7 m/s
  2. 3.1 m/s
  3. 3.8 m/s
  4. 10 m/s
  5. 19 m/s
  6. DAWWWW!!! PUPPIES!!!
  1. The figure below is the symbol of the Deathly Hallows (sort of), which entails a circle with a bar through its diameter circumscribed by an equilateral triangle. The circle has a mass and radius of 2.00 kg and 50.0 cm respectively, the bar through the middle has a mass of .500 kg, and each leg of the triangle has a mass and length of 1.00 kg and 120 cm respectively. What is the moment of inertia of this object if it is rotated about an axis perpendicular to its plane and through the point of its center of mass? (Ignore whether or not the legs of the triangle are of a physically impossible length.)
  1. 1.65 kg*m2
  2. 1.11 kg*m2
  3. 0.900 kg*m2
  4. 0.500 kg*m2
  5. 0.040 kg*m2
  6. This problem has no impact on my quest two find these three legendary items.
  1. An 80.0-kg fisherman is at one end of a 3.00-meter long wooden raft of uniform mass 30.0 kg. The boat is on a lake that has a very calm surface. The fisherman leaves his prime fishing spot at the end of the raft to grab a beverage from his cooler (you may assume the beverage and cooler to be massless), which is located at the midpoint of the raft. How much does the raft move relative to the surface of the water?
  1. 0.341 m
  2. 0.681 m
  3. 1.36 m
  4. 1.50 m
  5. 3.00 m
  6. I happen to be sitting on the other side of the raft, and I would ask the fisherman to toss me a beverage as well.
  1. A blacksmith has to pick up an iron blockof an unknown mass out of a hot furnace with a 3.00-meter long pole that has a mass of 2.00 kg. If the blacksmith lifts the mass and the pole with a force of 130 N coming from his right hand only a distance of 50 cm from the opposite end of the pole so that is rotationally and translationally stationary, what force must his left hand apply, and in what direction must he apply it?
  1. 98.5 N, upwards
  2. 98.5 N, downwards
  3. 107 N, downwards
  4. 130 N, upwards
  5. 130 N, downwards
  6. I’ll wait until after I take E M 274 to answer this question.
  1. Consider a uniform rod of length 1.00 m and a mass of 2.00 kg. One of the ends of the rod is hinged so the rod can rotate freely about an axis through that end. The rod is released from rest at the horizontal position. What is the angular speed of the rod when it reaches the vertical position?
  1. 3.13 rad/s
  2. 4.43 rad/s
  3. 5.42 rad/s
  4. 6.26 rad/s
  5. 7.00 rad/s
  6. Physics is hard.
  1. A ball of putty which can be considered a point mass strikes the tip of rod at an angle of 60º with respect to the horizontal (as shown below) that is fixed but able to rotate about its center of mass on a horizontal frictionless surface. The collision between the rod and the putty is completely inelastic. Initially, the putty is moving at a velocity of 3.00 m/s, and has a mass of 100 g. The rod has a mass of 2.00 kg, and is 2.00 m long. What is the angular velocity of the rod/mass system immediately after the collision?


  1. 0.097 rad/s out of the page
  2. 0.196 rad/s into the page
  3. 0.339 rad/s into the page
  4. 0.339 rad/s out of the page
  5. 1.95 rad/s out of the page
  6. I get dizzy when I think about rotating objects. Especially in physics.
  1. A sphere of uniform density has a radius of 2 m is placed in water. In order for it to float so that half of the sphere is submerged in calm water, what must the density of the sphere be? The density of the water is 1000 kg/m3.
  1. 500 kg/m3
  2. 750 kg/m3
  3. 1000 kg/m3
  4. 1333 kg/m3
  5. 2000 kg/m3
  6. I have no idea.
  1. You are an astronaut on a planet with a radius of 3.0*106 m. You grab a rock and drop it from a height of 3.0 m. The rock takes 1.0 s to reach the ground. What is the mass of the planet?
  1. 3.4*1023 kg
  2. 4.5*1023 kg
  3. 5.7*1023 kg
  4. 8.1*1023 kg
  5. 9.3*1023 kg
  6. I would abandon my study on the mass of the planet in order to search for extra-terrestrial life forms.