Physics Test 3- Work & Energy Flashcards
What is the formula for Kinematic Energy?
KE = 1/2(m)(v^2)
What is the formula for Spring Energy
EPE = 1/2(K)(X^2)
K is the spring constant.
X is distance.
What is the formula for Potential Energy?
PE = mass times gravity times height
Is Potential Energy Linear?
Yes
What is a Joule?
The unit for Energy. 1 Joule = 1 Newton times 1 meter
What is work?
Work is the product of a force and displacement that are in the same direction (parallel).
W = F(d)
Work is a squalor quantity
What is Power?
Power = work / time. Measured in Watts.
What are the 3 conditions for work to be done?
You need a force
You need a displacement
They need to be parallel
A vector times a squalor equals what?
A vector
A vector times a vector equals what?
A squalor
What are some examples of instances which energy could be lost?
Heat, friction, maintaining body temperature, replacing skin
Why is the human body less than 5% efficient?
Because keeping the body alive takes energy
What is Hooke’s Law?
Force = K(X)
What’s the definition of elastic?
Anything that can be deformed but will return to its original position. It does this with stored energy called ‘Elastic Potential’. This means it conserves kinetic energy.
What is the unit for a spring constant (K)?
Newton per meter
What is the proof for EPE = 1/2(K)(x^2)
Area of triangle = 1/2(b)(h) = 1/2 (x)(F) = 1/2(x)(kx) = 1/2(k)(x^2)
What are the stages of a vertical spring?
- Spring is compressed. All EPE
- Sprint begins to launch. No EPE. All PE and KE
- Spring is fully launched. All PE. Height and velocity are max
What are the stages of a horizontal spring?
- Spring is compressed. All EPE. Velocity = 0
- Spring is beginning to launch. All KE. Max velocity
- Spring is fully launched. All EPE. Velocity = 0
What are four spring examples?
- Bow and Arrow
- Pogo stick
- Slingshot example
- Small vertical spring and tennis ball.
What is a vector?
Any quantity in Physics with a size and a direction.
What are some other units for watts?
-Joules per second
-Newton times meter per second
-(Kilogram meter per second squared times meter)(second)
-Kilogram times a meter squared per second cubed
Who was James Watt?
A Scottish Engineer who made improvements to the steam engine. Tested Dray horses to discover horse power.
What is the formula for efficiency?
(Output/input)(100)
What is the Law of Conservation of Mechanical Energy?
ME = ME Prime
What is Mechanical Energy?
Energy with no friction or heat loss. Total energy is conserved
What is a conservative force?
Work is done on an independent path. No friction or heat loss.
What is a non conservative force?
Work depends on the path
What are examples of conservative forces?
Electric, gravitational, elastic
What are examples of non conservative forces?
Friction, applied, push-pull, tension
