Chapter 3: Momentum & Energy Flashcards Preview

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Flashcards in Chapter 3: Momentum & Energy Deck (18)
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1

Energy

The property of matter that gives it the ability to do work

2

Work

What is done when matter is moved against gravity

Work=force X distance w=Fd   Units = Newton*meters

(Nm) or Joules (J) 1Nm=1J

3

Potential Energy

Energy in a 'stored' state that has the potential to do work

Potential Energy= mass X gravity X height

derived from: 

gravitational potential energy = weight x height

4

Kinetic Engergy

What's being used when mass is moved;

Energy required to bring mass from rest to the speed it's at OR to bring is to rest from the speed it's at

Kinetic Energy=1/2(massXvelocity^2)  KE=1/2(mv^2)

1/2 is a constant

speed= delta displacement/delta time

5

Conservation of Energy for Machines

The work outpout of any machine cannot exceed the work input.

6

Efficiency

The percentage of the work put into a machine that is convered into useful work output

7

Collision: Elastic

A collision in which colliding objects rebound without lasting deformation or the generation of heat

8

Impulse

aka 'force time'; The product of the force acting on an object and the time during which it acts

Impulse=forceXtime

9

Impulse momentum relationship

Impulse is equal to the change in the momentum of an object that the impulse acts upon

Force Time = change in (momentumXvelocity)

10

Collision: Inelastic

A collision in which colliding objects become destorted, generate heat, and possibly stick together

11

Law of Conservation of Energy

Energy cannot be created nor destroyed.  It can only be transformed, and the total amount of engery never changes.

12

Law of Conservation of Momentum 

In the absence of an external force, the momentum (mass X velocity) of a system remains unchanged;

Momentum before an event involving internal forces is the same as after the event.

momentum before = momentum after

mv before = mv after

 

13

Lever

A simple machine consisting of a rigid rod pivioted at a fixed point called a fulcrum

14

Machine

A device, such as a lever or pylley, that increases or decreases a force or simply changes the direction of a force.

15

Momentum

Inertia in motion, given by the product of the mass of an object and its velocity

momentum = massXvelocity

M = mv

16

Power

The rate of doing work (or the rate at which energy is expended)

Rate at which energy is transformed from one form to another.

Power = work/time  Unit is Watt (same as Joule/second)

17

Work-Energy Theorem

The net work done on an objects equals the change in kinetic engergy of the object

Work done on object = change in kinetic energy

The more kinetic energy something has, the more force is required to stop it.

18

Watt

Unit for power;  same as one Joule/second)