chapter 9 Flashcards

(34 cards)

1
Q

potential energy is associated with…

A

position

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2
Q

kinetic energy is associated with….

A

motion

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3
Q

what is energy measured in

A

Joules

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4
Q

What is Work

A

a process that changes the energy of a system by mechanical means, pushing or pulling

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5
Q

what’s the energy principle

A

energy cannot be created or destroyed,

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6
Q

What is power

A

the rate at which energy is transferred or transformed

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7
Q

symbol for kinetic energy

A

K

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8
Q

Symbol for potential energy

A

U

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9
Q

whats the environement

A

objects external to the system but exerting forces on the system

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10
Q

whats the system

A

objects whose motion and environment we wish to analyze

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11
Q

law of conservation of energy

A

As long as the system is not interacting with the environment, the total energy of the system is unchanged.

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12
Q

interactions with environment

A

can transfer energy in and out of the system

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13
Q

Two ways to transfer energy

A

through work (pushing or pulling using forces) or thermal means

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14
Q

energy principle formula

A

(triangle)Esys= Wext

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15
Q

energy is transformed within the system without

A

loss

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16
Q

energy is transferred to and from the system by

A

forces of the environment

17
Q

The energy of an isolated system—one that doesn’t interact with its environment—does not change. We say it is

18
Q

draw a before and after representation of a particle of mass m acted on by a constant force acting parrallel

19
Q

kinetic energy equation

20
Q

if kinetic energy is negative the particle….and if its positive….

A

slows down, speeds up

21
Q

all forms of energy are measured in

22
Q

whats the kinetic energy of a .5kg mass moving at 4m/s

23
Q

A 1000 kg car has a speed of 20 m/s. A 2000 kg truck has a speed of 10 m/s. Which has more kinetic energy?

24
Q

tell me every part of this equation: (triangle)K=Kf-Ki=W

A

change is sutems kinetic energy=final kinetic energy - inital kinetic energy (aka amount of work done by external force)

25
A 5.0 kg cannonball is fired straight up at 35 m/s. What is its speed after rising 45 m?
18m/s
26
If the force causes the particle to speed up, then the work done by that force is
positive
27
negative work means that the force is causing the object to
slow and lose energy
28
work is positive when the force acts in the direction of the
displacement
29
work is negative when force and displacement are
in opposite directions
30
When work = 0, the particle
does'nt move
31
A rock falls to the bottom of a deep canyon. Is the work done on the rock by gravity positive, negative, or zero
positive, displacement and gravity both downwards
32
A force perpendicular to the displacement does
no work
33
Two equal-mass pucks on frictionless ice are pushed toward each other by two equal but opposite forces. Is the total work positive, negative, or zero?
zero
34