Chapter 13: Work, Energy and Power. Flashcards
What is the formula for Work Done?
Work Done = Force x Distance.
What Units does Work Done have?
Joules (J).
What Units does Force have?
Newtons (N).
What Units does Distance have?
Metres (m).
What is the formula for Power involving Work Done and time?
Power = Work Done/ Time taken.
What Units does Power have?
Watts (W).
What Units does Time have?
Seconds (s).
What are the formulas for Power?
- Power = Force x Velocity.
- Power = Work-done/ Time.
What is the formula for Gravitational Potential Energy?
GPE = mgh.
What Units does Energy have?
Joules (J).
What Units does Mass have?
Kilograms (kg).
What Units does Acceleration due to Gravity (g) have?
Metres per second squared (m/s²).
What Units does Height have?
Metres (m).
What is the formula for Kinetic Energy?
KE = 1/2 mv².
What Units does Velocity have?
Metres per second (m/s).
What is the equation for Newtons Second Law?
F = ma.
What is the conservation of energy principle?
Kinetic Energy (KE) gained = Gravitational Potential Energy (GPE) Lost. Vice versa.
What is the formula for the Work-Energy Principle?
Work Done = Change in GPE + Change in KE.
What is the formula for Hooke’s Law?
T = λx/ l (natural length).
What does the ‘x’ mean in Hookes Law and what is its Units?
Extension - Metres (m).
What does the ‘l’ mean in Hookes Law and what is its Units?
Natural/ Unstretched Length - Metres (m).
What is the formula for Stiffness (k)?
k = λ/ l (natural length).
What is the formula for Elastic Potential Energy?
EPE = λx²/ 2l.
What are the Units of the Modulus of Elasticity (λ)?
Newtons (N).
If a string or spring goes beyond its elastic limit what happens?
It becomes permanently deformed and Hooke’s Law won’t work as it won’t return to its original shape.
What is the equation for Work Done by all external forces?
Work Done = change in GPE + change in KE + change in EPE.
