Chapter 7: Kinetic Energy & Work Flashcards

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1
Q

What is energy?

A

It is a quantity that specifies important information about the state of a system–notably, the ability of the system to cause change in physically measurable properties of its environment.
SI unit: joule (J) = kg * m^2/s^2 = n * m

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2
Q

Is energy a vector quantity?

A

No! It is a scalar quantity!

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3
Q

Energy comes in three basic forms: ___, ___ and ___.

A

Kinetic energy; potential energy (gravitational, elastic, electrostatic); rest energy.

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4
Q

Energy can be transformed from one form to another, and the total energy of a closed system (can)/(cannot) change.

A

Cannot

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5
Q

What is kinetic energy?

A

The energy a particle has because of its motion. K = 1/2 * m * (V(subx)^2 + V(suby)^2 + V(subz)^2)

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6
Q

What is work?

A

The transfer of energy between a system and its surroundings by means of a force.

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7
Q

Work is done by a ___.

A

Force

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8
Q

Work done by a constant force is:

A

W(subf) = F(arrow) * Δr

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9
Q

Is work a vector quantity?

A

No! It is a scalar quantity.

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10
Q

When work is done by the ___ forces acting on a particle, energy is transferred to or from the particle.

A

External

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11
Q

W(net) = …

A

ΔK = K(sub2) - K(sub1)

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12
Q

If W(subnet) > 0, then ΔK ___ 0.

A

>

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13
Q

If W(subnet) < 0, then ΔK ___ 0.

A

<

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14
Q

If W(subnet) = 0, then ΔK ___ 0.

A

=

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15
Q

TRUE or FALSE: Forces perpendicular to the motion of the object do work.

A

False! They do no work.

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16
Q

Work done by the gravitational force is demonstrated by the formula W(subgrav) = …

A

-mgΔy

17
Q

Work done by gravity (is affected by)/(is not impacted by) horizontal distance traveled.

A

Is not impacted by

18
Q

What is Hooke’s Law?

A

F(subs) = -kΔx

19
Q

The SI unit of the spring constant K is…

A

N/m

20
Q

A larger value of K means a ___ string.

A

Stiffer

21
Q

You can use F(subs) = -kΔx as long as the equilibrium position is ___.

A

The origin

22
Q

When the work done by the spring constant isn’t constant, you (can)/(cannot) use the standard formula for work.

A

Cannot

23
Q

Use either ___ or an ___ to get the area under the curve on a graph of ___ vs. ___ to get the work for a specific distance.

A

Summation; integral; force; distance.

24
Q

On a frictionless banked curve, F(subn) supports (more)/(less than) the weight of the object, meaning F(subn) ___ mgcosθ.

A

More; >

25
Q

When there is no friction on a banked curve, ___, or ___. This is because the normal force on a banked curve has to support the entire weight of the object and provide the centripetal force necessary to keep it in motion.

A

F(subny) = mg; F(subny) = F(subn)cosθ = mg

26
Q

If there is not friction, there is a(n) (exact speed)/(range of speeds) where an object will not slip and move up or down the incline.

A

Exact speed

27
Q

On a banked curve WITH friction, the setup for the equation is the same as without it–except, this time, a friction force directed (up)/(down) the incline, with magnitude ___, must be factored into the equation.

A

Down; μF(subn)

28
Q

What is power?

A

The work done over a set time interval.
SI unit: Nm/s = J/s = W (watt)

29
Q

Instantaneous power due to applied force is:

A

P(subF) = F(arrow) * v(arrow)