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This is the Past Paper of General Physics which includes Cause of Object Motion, Force Exerted, Terms of Energy, Object’s Motion, Presence of Gravitational Force, Coefficient of Static Friction, Initial Velocity, Platypus by Gravity etc. Key important points are: Average Thrust in Newtons, Perfectly Elastic Collisions, External Forces, Absence of Forces, Momentum of Rocket, Motor Designation, Burn Time of Rocket Motor, Final Vertical Speed
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St. Vincent College PH 111: General Physics I
The exam consists of 4 questions. There will be 50 minutes to complete the exam. The questions may not be worth the same number of points, read the entire exam before beginning work. Put your name on all pages.
Problem 1 20
Problem 2 25 Problem 3 25
Problem 4 30
Total 100
a) (5 pts) Cite at least one real physical example of perfectly elastic collisions (where both momentum and energy are conserved).
b) (5 pts) A certain impulse is required to stop a fist from moving, depending on the speed of the punch and the mass of the hand. Explain why it would hurt less (to stop the fist) if you allow your body to be limp rather than holding yourself rigidly.
c) (5 pts) A car moving south collides inelastically with another car initially moving east. The crumpled aftermath remains stuck together. How can we determine in what (general) direction the smashed wreckage will be moving after the collision? (Oh, and in what general direction will the wreckage be moving in this collision?)
d) (5 pts) In space there’s no one to hear you scream nor anything for rocket exhaust to “push against.” Explain why, when the rocket spews exhaust out one end, the rocket itself must move in the other direction. Note out in space there will be no external forces acting on the rocket/exhaust system. Thus you cannot make reference to these forces in your explanation (at least if you want to explain it correctly).
40 kg: r~ 1 = 2ˆi + 2ˆj m, v~ 1 = 3ˆi − ˆj m/s 50 kg: r~ 2 = 3ˆi − 3 .5ˆj m, v~ 2 = − 3 .5ˆi + 3.5ˆj m/s 55 kg: r~ 3 = −2ˆi − 1 .5ˆj m, v~ 3 = 3.7ˆj m/s
40 kg
50 kg
55 kg
a) (10 pts) Determine the location of the center of mass of the group.
b) (10 pts) What is the current velocity of the center of mass?
c) (5 pts) What is the total momentum of the group? (This could be done in either of two ways.)
d) (5 pts) Do you suppose the momentum of this group of skaters will be conserved? Explain why or why not. And what effect would this have on the motion of the center of mass?
