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Chapter 4 Notes

Terms in this set (39)

when is work done?
when a force causes an object to move in the direction of the force (the object moves as the force is applied, the direction of motion is the same direction as force)
how do you calculate work?
W = F x d (force x distance)
unit for work - Joules
which takes more work? hiking up a long but gentle winding path or climbing up a sheer cliff?
the same amount of work
what is power?
the rate at which energy is transferred
how do you calculate power?
P = W/t (work/time)
unit for power - watt
the faster work is done...
the more power is required
how does a machine make work easier?
1. changes the sizes of a force and/or
2. changes the direction of a force
the work you do on a machine is called
work input
work input = force in X distance in
the work done by a machine on an object is called
work output
work output = force out X distance out
how do machines help
- they make your work easier but they do not increase the amount of work done (work output can NEVER be greater than work in put)
*balance out
- small distance = bigger force
- machines : make work easier but you have to do more
why do machines make it seem like less work?
the machines allow the force to be exerted of a greater distance (use less force but apply it for a larger distance)
when a machine changes the size of the force the (blank) must change too
distance
when one increases the other has to decrease
force in x distance in = force out x distance out
what is mechanical advantage?
the number of times the machine multiplies a force (compare input force with output force)
how do you calculate mechanical advantage?
MA = output force/ input force
ideal MA = length / height
- a machine with a MA of >1 helps moving because the output force is greater than the input force
- a machine with a MA of <1 will reduce the output force but increase the distance an object moves
what does IMA stand for?
ideal mechanical advantage
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