1What is work used to calculate?
Effect of forces acting on a body in terms of energy
2What is the equation for work?
W = F x
3What is the equation for work-done at an angle?
W = Fxcos(0)
4What does the conservation of energy state?
Energy can be transferred between multiple forms but is never created nor destroyed
5How many types of energy are there? What are they?
3
Gravitational potential energy (GPE)
Elastic potential energy (EPE)
Kinetic energy (KE)
6What is the equation for GPE?
ΔEp = mgΔh
(m=mass, g=gfs, Δh= change in height of body)
7What is the equation for EPE?
Ep = 1/2kx^2
(k=spring constant, x=spring extension)
8What is the equation for KE?
Ek = 1/2mv^2
(m=mass, v=speed)
9What will a body falling toward earth lose? What will it gain?
Lose gravitational potential energy (gpe)
Transferred to kinetic energy as speeds up
10What happens when a spring is released, what does it lose?
Lose elastic potential energy
11What does the work energy relationship relate?
Relates the work done by constant force on body to kinetic energy of body
12What is the work energy relationship equation?
Fx = 1/2mv^2 - 1/2mu^2
13What does the work energy relationship equation demonstrate?
That the work done on a body = the change in kinetic energy of that body
14What is power?
Rate of transfer of energy /
Power is the rate of doing work (if include work)
15What is the equation for power?
Power = energy transferred/work done
—————————————-
time
16What are dissipative forces?
Forces that reduce the efficiency of a system
17What do dissipative forces reduce?
Useful energy, eg. kinetic
18What do dissipative forces produce?
Un-useful energy, eg. heat
19What are examples of dissipative forces?
Drag
Friction
20Example of friction being a dissipative force?
Friction on car tyre, reduces KE produced by engine
Heats up the tyres reducing performance
21Example of drag being a dissipative force?
Drag on aeroplane, larger energy output required from engine to maintain speed
22How are vehicles adapted to reduce drag and friction?
Sports cars have pointier front so air can flow over easier
23What do athletes (cyclists) do to reduce air resistance acting on them?
Wear tight clothing and special headgear
24What is the equation for energy efficiency?
Efficiency = useful energy transfer
————————————————- x 100
total energy input
25What is the theoretical efficiency of a system?
The max theortical efficiency of system is 100% bc u cant transfer more energy than u put in (conservation of energy)