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Flashcards in Chapter 5 Deck (16)
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1

Work

-Equal to the product of the magnitudes of the displacement and the component of the force parallel to that displacement
-Force but no displacement= no work
-SI: Joule (J)
-Scalar quantity

2

When is work positive?

-The force (or component) is in the direction of motion (and displacement)
-Ex: pushing a box

3

When is work negative?

-The force (or component) is opposite to the direction of motion (and displacement)
-Ex: catching a ball

4

Kinetic Energy

-The energy of motion
-when an object is moving with a constant acceleration due to an applied force
-Net force causes object to accelerate, changing velocity
-SI: J
-Scalar quantity

5

Work-Kinetic Energy Theorem

-The net work done by all the forces acting on an object is equal to the change in the object's kinetic energy

6

Potential Energy

-(U or PE) The energy associated with an object because of the position, shape, or condition of the object
-Released into kinetic energy
-Types: Gravitational and Elastic

7

Gravitational Potential Energy

-(Ug or Pg)The potential energy stored in the gravitational fields of interacting bodies
-SI: J
-Greater potential with greater height, less potential with less height

8

Elastic Potential Energy

-(Ue or Pe) The energy available for use when a deformed elastic object returns to its original configuration

9

Hooke's Law

-When in equilibrium ( a mass is hanging at rest)< we can say the ideal spring force is F(s)= k(delta X or delta y)

10

Conservation of Energy

-The total energy of an isolated system is always conserved

10

Non conservative Force

-If work done by it in moving an object, it does depend on the objects path
-Ex: Friction

11

Conservative Force

-Work is done by moving an object and is independent of the objects path
-Work done by it in an object through a round trip=0
-Ex: Gravity

12

Power

-The rate at which work is done
-Inversely proportional to time
-Directly proportional to work

13

Efficiency (Mechanical Efficiency)

-Unitless (joules cancel out)
-Less than 100%

14

Total Mechanical Energy

-The sum of all kinetic energy and all forms of potential energy

15

Horsepower

-1 horsepower= 750 watts