Formulas and SI Units
Work, work, work, work and power!
Energetics
Miscellaneous
More Miscellaneous!
100
Formulas for Work and SI units
W = F d cos (theta)


or

W = F d

Units:  Joules

100
This is created when a force acts on an object and the object moves in the direction of the force.  
Work
100
The ability of something to cause a change is its ____________.
energy
100
State the Law of Conservation of Energy
Energy cannot be created nor destroyed, but it can be transformed from one energy to another.
100
If two cats equivalent in size run down a street past three cars.  The tabby cat runs faster than the black cat.  Which cat does the most work?  Which has the most power?  
They use the same work because they are the same mass and run the same distance (W = F d).


The tabby cat uses more power, though, because it runs faster, reducing the time, which increases the power.  (P = W/t)

200
Formula for Power and SI unit
P = W/t


Watts

200
Work is _________ proportional to distance and force.
directly
200
Energy due to an object's position
Potential energy
200
When an object is thrown upwards, where is it most likely to have the most potential energy and kinetic energy?  
Potential energy is highest at the peak of travel because it has a greater height.


Kinetic energy is greatest at the bottom of the arch of travel because the potential energy is transformed into kinetic energy

200
Which variables affect a pendulum period?  
Length and release angle.  NOT mass.  
300
Formula for Potential energy and SI units
PE = m g h


Joules

300
When a student walks and then runs up the same flight of stairs, the student requires the same amount of ____________, but the _________ used is changed.
work; power
300
Energy created by movements of electrons; the easiest for us to transport
Electrical energy
300
As you increase the speed of an object, what physics terms are also increased?  
Kinetic energy and momentum
300
Formula for impulse-momentum theorem

(delta)p = mvf - mvi


SO

F t = mvf - mvi

400
Formula for Kinetic Energy and SI unit

KE = 1/2 m v2


Joules

400
The rate at which something is doing work is the ______________.  
power
400
Energy from splitting or fusing atoms
Nuclear energy
400
State which of the following are scalar/vector:

Work

Momentum

Force

Mass

Work -Vector

Momentum -Vector

Force -Vector

Mass-Scalar

400
What are three ways a machine can make work easier?  
1. Change the amount of force

2. Change the direction of the load

3. Change the distance the load travels

500
Formula for momentum and SI unit for momentum
p = m v


kg m/s

500
A person is carrying a box across a room at waist level.  Is this person doing work in reference to the box? 
No, the force applied is not in the direction of the object's motion.  
500
This is often the cause of some form of energy being transformed into thermal energy.
Friction
500
Why does a boxer move his head with the punch rather than hold still for it?  
If the boxer holds still, he takes the full force of the impact, as we can see from the impulse formula.  If the boxer moves his head in the direction of the punch, he increases impact time which will reduce the force of impact.  
500
Formula and SI unit for impulse
(Delta) p = F t


Ns

M
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n
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