Work, Energy and Power Flashcards
what is the conservation of energy
total energy before = total energy after
what is work
when energy is added to or removed from a system
when is work done
work is done when a force is applied to an object and the object moves in the same direction as the applied force
what is the formula for work
wd = F x s
how do you find the work of an object at an angle
you use the component of force that is in the same direction as the motion
what is the formula for work at an angle
W = Fscostheta
maria walks up a 3 meter tall staircase in 15s. Paige runs up it in 5s. Who does more work
they do the same amount of work cos work only depends of force and distance
what is power
the rate at which work is done
what is the relationship that links power and work done
power = work done/time
what average force is needed to slow a car of mass 1200kg from 30 ms-1 to 10ms-1 over a distance of 50m?
Wd = Fs
Wd = final ke - initial ke
Wd = 60000-540000 = -480000J
Wd/s = F = -480000/50
F = -9600N
what is a joule in si units
ke = 1/2mv2
kg(ms-1)^2
= kgm2s-2
what is a watt in si units
kgm2s-3
what does the area under a force distance graph equal
work done
what is hookes law formula
F = kx
what is the formula for elastic potential energy
1/2k(delta(x))^2
when is the elastic potential energy formula used
for a non-constant force
A system that consists of a single spring stores a total elastic potential energy Ep when a load is added to the spring. Another identical spring connected in parallel is added to the system. The same load is now applied to the parallel springs. What is the total elastic potential energy stored in the changed system?
https://www.youtube.com/watch?v=D50iNfj-qik
An increasing force acts on a metal wire and the wire extends from an initial length l0 to a new length l. The graph shows the variation of force with length for the wire. The energy required to extend the wire from l0 to l is E. The wire then contracts to half its original extension.
What is the work done by the wire as it contracts?
https://www.youtube.com/watch?v=QBEzkeuYOn4
