Review Exercises for Exam 2
Studio Physics I
The purpose of this activity is to help you prepare for Exam 2. Questions on this exam are similar to past Physics I exam questions. Please answer the questions on your own paper as we will need the questions for the next section. You may discuss the questions with other students, your TAs, and your instructor. However, your TAs and instructor cannot tell you the correct answers, only discuss the general principles of physics that apply. Everyone must submit his or her own answers. We will grade your answers to the questions for your activity grade.
Part A – Multiple Choice – 0.5 Points Each
______1.Let g = the acceleration constant of gravity. For a block of mass m to slide without friction up the rise of height h shown, it must have a minimum initial speed of:
______2.Two automobiles skidding on an icy road collided and became entangled (stuck together). Luckily, no one was injured! Which principle of physics below could you not correctly use when analyzing the collision for the insurance companies? (Assume road friction and air resistance were negligible during the crash.)
A)Conservation of linear momentum.
B)Conservation of angular momentum.
C)Conservation of mechanical energy (kinetic plus potential).
D)The Impulse-Momentum Theorem.
E)The Work-Kinetic Energy Theorem.
______3.A car is heading north at 100 km/hr when the driver steps on the brakes. While the car is slowing down, what is the direction of the net torque on the wheels?
A) Up (Toward the Sky).
B) Down (Toward the Ground).
C) North.
D) South.
E) East.
F) West.
______4.A competitor in the Olympics springs off a diving board and attempts a triple-somersault dive. While she is in the air, neglecting air resistance, she cannot change her
A)Rotational kinetic energy.
B)Rotational inertia.
C)Angular momentum.
D)Angular velocity.
Part B – Graphing – 2 Points
We fire a toy cannon at an angle of 60° with respect to horizontal. The projectile is in the air for 2.0 seconds before it comes back to the same height from which it was launched. The mass of the plastic projectile is 10.0 grams. The initial location of the projectile is (0.0,0.0) meters. Use g (gravity acceleration constant) = 9.8 m/s2. Neglect air resistance.
Plot PE and KE as functions of time from 0.0 to 2.0 sec. Show the following features.
1. Shapes of the curves.2. Maximum/minimum points.3. Values at t = 0, 1, 2 sec.
Part C – Problems
C-1 – 1 Point
A DJ is playing a vinyl record spinning at 33 ⅓ revolutions per minute when the power goes out. The turntable coasts to a stop with a constant acceleration due to friction torque of the bearings. The rotational inertia of the turntable with the record is 1.46 x 10-2 kg m2. The bearing friction torque is –3.87 x 10-5 N-m. How many revolutions does the turntable turn before stopping?
C-2 – 2 Points
Two spherical drops of water of equal mass floating inside the shuttle Atlantis are each spinning at 1.00 rad/s in the same direction, too slowly to cause the respective drops to deform significantly. They collide gently along a line connecting their centers and coalesce into one spherical drop. What is the rotation speed of the combined drop? Use .
C-3 – 3 Points
Cart 1, mass = 1.0 kg, is compressed 4.0 cm against an ideal spring with spring constant of 5625 N/m. It is released and moves to the right on a frictionless track to collide with cart 2, mass = 0.5 kg, initially at rest. The collision is elastic. Cart 2 proceeds up a curved ramp until it reaches its highest point. How high does cart 2 go? Use g (gravity acceleration constant) = 9.8 N/kg.