Energy and Work

Question 1

What is Kinetic Energy formula?

Answer 1

KE = 1/2(mv^2) (unit: J)

Question 2

What is Gravitational Potential energy?

Answer 2

U = mgh (unit: J)

Question 3

What is Elastic Potential energy?

Answer 3

U = 1/2kx^2 (unit: J)

k: spring constant
x: displacement from equilibrium

Question 4

What is the total mechanical energy?

Answer 4

E = KE + U

E = mechanical energy
KE = kinetic energy
U = potential energy

Question 5

What is the 1st law of Thermodynamics?

Answer 5

Energy is not created/destroyed

Question 6

What is equation for Work in terms of force and displacement?

Answer 6

W = F*d cos θ
θ = angle between applied Force and Displacement vector

Question 7

What is the equation for pressure and volume?

Answer 7

W = PΔV

Question 8

What is the equation for Power in terms of work?

Answer 8

Power is rate at which E is transferred.

P = W/t or ΔE/t (unit: J/s)

Question 9

What is Work-Energy theorem?

Answer 9

The net work is equal to change in KE
W(net) = ΔKE = Kf - Ki

-W = done on the system
\+W = done by the system

Question 10

What is Mechanical advantage?

Answer 10

MA = F(out) / F(in)

Question 11

What is Efficiency?

Answer 11

W(out) / W(in) = (loadload distance) / (efforteffort distance)

output: work done by machine
input: work done on machine