Term
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Definition
| is measure of an objects tendancy to continue on it's present path |
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Term
| how can the momentum of an object increase |
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Definition
| increase the velocity, or increase the mass |
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Term
| what is the equation for momentum and what are it's units |
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Definition
p=mv
momentum's units are: kg m/s |
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Term
| in an isolated system, what is the number one inviolable rule of momentum |
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Definition
| that momentum is always conserved |
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Term
| momentum is also a vector, what does this mean in terms of initial momentum and final momentum |
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Definition
| the initial momentum of the center of mass is equal to the final momentum in both direction and magnitude |
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Term
| Describe what an elastic collision is |
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Definition
| When two bodies come into contact with one another, the force generated by the deformed bodies is proportional tothe degree of the deformity. If Hooke's Law is followed, the energy is conserved, and all the energy is transferred back into the motion of the bodies |
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Term
| Why are elastic equations easy |
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Definition
| Because the sum of the initial mechanical energies is equal to the final sum of mechanical energies |
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Term
| what are inelastic collisions |
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Definition
| These are collisions in which some of the mechanical energy is lost to internal energy |
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Term
| If any mechanical energy is lost, what type of collision is this |
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Definition
| This is an inelastic collision |
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Term
| What is a completely inelastic collision |
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Definition
| When two objects stick to each other |
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Term
| What is a reverse collision |
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Definition
| In a completely inelastic collison, two bodies will stick together and their final momentum equals zero. Therefore, the initial momentum equals zero. To understand a reverse collision mechanism, think of these objects as intially being stuck together and then exploding. The initial momentum is zero, so therefore the final momentum is zero. |
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Term
| What is the equation for a reverse equation, and give an exmaple of it. |
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Definition
A cat is standing on a frictionless board on a frictionless frozen lake, when it jumps to the right, the board must be pushed to the left to conserve energy.
M1V1=M2V2 |
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Term
| When does a partially inelastic collision occur |
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Definition
| When a object moving at velocity strikes another object that is stationary but of equal mass to the first object. |
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Term
| The context is: this is a partially inelastic mechanism. Describe how to find the final velocity of the stationary object and the moving object |
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Definition
The stationary object will be less than the initial velocity of the moving object, but greater than the initial velocity divided by 2.
The moving object will be greater than zero, but less than the initial velocity divided by 2. |
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Term
| In a partially inelastic mechanism, is it possible that a moving object could strike a stationary object and bounce backwards |
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Definition
| Yes. If the stationary object has a large enough mass, it could potentially send that moving object backwards after the collision. |
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Term
| what is impulse and give its equation |
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Definition
| The change in momentum, J= delta P |
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Term
| Context: If a collision approximately follows Hooke's Law, the force during the time of collision is not constant. How can we find the average force from that change in momentum |
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Definition
| delta MV= F avg * delta t |
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Term
| Explain how air bags work |
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Definition
| If the change in time is increased, we know that the average F exerted on a person is decreased. therefore, air bags simply increase the amount of time it takes for the change in momentum to occur, thus lowering the overall force exerted |
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