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Test 3 phy science
gravity, momentum and energy
Question | Answer |
---|---|
In the absence of external work input or output, the energy of a system remains unnchanged. Energy cannot be created or destroyed. | Conservation of energy |
The work output of any machine cannot exceed the work input. In an ideal machine, where no energy is transformed into heat, work input = work output and (Fd)input=(Fd)output | Conservation of energy and machines |
In the absence of an external force, the momentum of a system remains unchanged. Hense, the momentum before an event involving only internal forces is equal to the momentum after the event: mv(before envent)=mv(after envent) | Conservation of momentum |
The percentage of the work put into a machine that is converted into useful work output. (It is useful energy output divided by total energy input) | Efficiency |
A collision in which colliding objects rebound without lasting deformation or the gereration of heat. | Elastic Collision |
The property of a system that enables it to do work | Energy |
The product of the force acting on an object and the time during which it acts. | Impulse |
A collision in which the colliding objects become distorted, gererate heat, and possibly stick together. | Inelastic collision |
The SI unit of energy and work, equivalent to a newton-meter | Joule |
Energy of motion, descrived by the relationship... ____________=1/2mv^2 | Kinetic Energy |
The product of the mass of an object and its velocity | Momentum |
The stored energy that a body possesses because of its position | Potential energy |
The time rate of work:__________=work/time (the rate at which energy is expended) | Power |
Impulse is equal to the change in the momentum of the object upon which the impulse acts. Ft=(triangle)mv | Relationship of impulse and momentum |
The product of the force and the distance through which the force moves: _____=Fd | Work |
The work done on an object equals the change in kinetic energy of the object: Work=(triangle)KE | Work-Energy Theorem |
Any force that is directed at right angles to the path of a moving object and that tends to produce circular motion. | Centripetal force |
The attractive force between objects due to mass | |
Law relating the intensity of an effect to the inverse square of the distance from the cause: Intensity~ 1/distance^2 | Inverse-square law |
Every body in the universe attracts every other body with a mutually attracting force. For two bodies, this force is directly proportional to the product of their masses and inversely proportional to the square of the distamce sep. them | Law of universal gravitation |
The curved path followed by a projectile near the Earth under the influence of gravity only. | Parabola |
Any object that moves through the air or through space under the influence of gravity | Projectile |
Velocity that is parallel to a curved path | Tangential velocity |
The proportionality constant in Newton's law of gravitation | Universal constant of gravitation, G |
A condition encountered in free fall wherein a support force is lacking | Weightlessness |