Unit 1.4 Energy concepts Flashcards
(46 cards)
Define work.
It is done when a force moves its point of application.
Define energy.
The energy of a body or system is the amount of work it can do.
Give the units for work.
Joule (J)
What type of quantity is energy?
Scalar quantity
What is kinetic energy?
Energy due to motion.
State the formula work done.
Work done = Force x Distance moved in the direction of the force
State the formula for work done in symbols.
W = Fx
Give the units for the symbol “W”, in work done formula.
(J) - Joules
Give the units for the symbol “F”, in work done formula.
(N) - Newtons
Give the units for the symbol “x”, in work done formula.
(m) - metres
State another way of saying work done.
Energy transfer
Explain energy.
Quantity of energy transferred is equal to the work done by force.
State 2 other formulas for work done.
(1) Work done = Force x Component of displacement in the direction of the force
(2) Work done = Component of force in the direction of displacement x Displacement
State the 2nd formula of work done in symbols.
W = Fxcosθ
Explain in terms of energy, if θ = 90°
No work is done; no energy is transferred.
Explain in terms of energy, if θ > 90°
The work is negative and energy is transferred from the object.
State the principle of conservation of energy.
The total energy of an isolated system is constant though it can be transferred within the system.
State the principle of conservation of energy in symbols.
ΔE - FvΔt - FvΔt = 0
What does the principle of conservation of energy mean?
Work done = energy transfer
Define kinetic energy (KE or Eₖ).
The energy possessed by a body by virtue of its motion.
State the formula for KE.
KE = 1/2 mv²
Explain the formula for KE.
It is the KE of a body of mass “m” travelling with velocity “v”.
Define gravitational potential energy (GPE or PE or Eₚ).
The energy possessed by an object by virtue of its position.
State the formula for GPE.
ΔEₚ = mgΔh
