Work, Energy and power Flashcards
What is work
What happens if work is negative
The amount of energy a force exerts on an object or transfers from an object
The force is taking away energy from an object
What are the equations for work
W= FDcostheta
W= Delta(E)
What does the work-energy theorem say
Work done by a net force is equivalent to the change in kinetic energy
What is the relationship between kinetic and potential energy if mechanical energy is conserved
Change in kinetic energy is equivalent to the negative change in potential energy
When is mechanical energy not conserved
When non conservative forces are in play, like drag, air resistance, and friction
What is a conservative force
How is potential energy related
Examples of conservative forces
A conservative force is a force whose path is independent from the displacement path
Potential energy = negative work done by conservative force
Gravity and Elastic springs are examples
What is the equation for gravitational potential energy
Ug= mg(y)
What is the equation for the force of a spring
What is the work done by the force of a spring
Fs= Kx, where K is the spring constant and x is the displacement
Us= 0.5Kx² , the integral of force
How do you calculate work for a non constant force given a force v displacement graph
You take the integral of the function
When mechanical energy is not conserved, what is the relationship between kinetic energy, potential energy, and non conservative forces
Mechanical energy = KE + PE + work done by non conservative force
What is power
Work/time
change in mechanical energy over time
What is work and energy measured in? What about power?
Work and energy is measured in Joules, Power is measured in Watts.
Halfway through free fall what is the kinetic energy of an object? What about the potential energy? Only if air resistance is negligible.
(Hint, fraction)
1/2 of KE and 1/2 of PE
How do you calculate the work if the force is not constant.
You take the integral of a force v displacement graph.
