Lets start with work.
Work is the transfer of energy.
Work = force x distance
Force and distance must be parallel to have work
If the force does not cause the object to move than there is
no work done.
You are exerting a force on something for some distance
Work and energy are both measured in joules
Joules are actually just Newtons per meter.
How is work related to power and Kinetic energy?
Work
= change in Kinetic Energy
Power= work/time
When
we did the lab, what we learned is that work = forcexdistance and that this
distance is always the vertical height. When we walk up the stairs or we run up the stairs, we do
the same amount of work as long as our weight (force) and the distance (height
of the stairs) remains the same. Well why wouldn’t you be doing more work if
you were running? Time has no factor in the work equation, so if you do the
same thing in less time, the only thing you do more of is generate more power.
And why is that? Power does have time factored into its equation. Power =
work/time. The less time you have, the more power you generate. Notice that the definition of power is how
quickly work is done, so the reason the equation is work/time is self explanatory.
How is work related to Machines?
Work = F XD
(THIS IS AN EXAMPLE OF WHY THERE IS OR IS NOT ANY WORK DONE)
remember that because of this work is not force.
the equation acts more like a balance when dealing with machines. Machines decrease the force and increase the distance. However: the work is always the same. If the work is the same then the kinetic energy is the same. If the kinetic energy is the same then the potential energy is the same in machines as before.
Using machines:
You can never get more work out than the work you put in. However pay attention to the difference of "missing work" and putting and getting out work. Say that something requires a specific amount of work to be lifted and you have to put 20 more j of work in to lift it.. the missing work would be expelled as light, heat, or sound. This is why we hear engines and see light and engines are hot-> because they are not 100% efficient machines. Remember that you can never get more work out than you can put it and that the numerator in a fraction is always smaller than the denominator= so that's why workout is divided by work in and work out is in the numerator position because it will always be smaller.
Kinetic Energy is the energy of movement. Potential energy is the possible energy an object will have.
Kinetic Energy= one half x m x vsquared
Potential Energy= Mass times gravity times height
Change in ke = change in pe
Potential energy is always at the top of a hill--- because its the energy that has not happened yet but could happen
Kinetic energy is the energy of movement, the energy at the bottom of the hill because it has moved.
When we swing, the starting point and ending points are the potential energy while the very bottom middle is kinetic energy and the lines dividing the middle and both of the end points are pe= ke
