Work and energy are related, since energy is always ____ from the object doing the work to the object on which the work is done.
Work is done on an object only when a ____ is being applied to the object and the object moves.
Since work and energy are _____, power also can be calculated.
related, power equals energy divided by time.
Machines _____ applied force and/or _____ direction of applied force to make work easier.
same amount of work can be done by applying a small force over a long distance as can be done applying a large force over a short distance, since work equals _____ times _____.
The amount of energy the machine transfers to the object cannot be _____ than the amount of energy transferred to the machine
Mechanical advantage (MA)
is the number of times a machine multiplies the effort force. It is calculated by MA equals resistance force divided by effort force.
Measure of how much of the work put into a machine is changed into useful output work by the machine.
Three classes of levers based on positions of ____ ____, ____ ____, ____
effort force, resistance force and fulcrum
First class lever
fulcrum is located between the effort and resistance forces; multiplies and changes direction of force (screw driver).
Second class lever
resistance force is located between the effort force and fulcrum always multiplies force (wheel barrel)
Third class lever
effort force is between the resistance force and fulcrum; doesn't multiply force but does increase distance over which force is applied (baseball bat)
Calculating ideal mechanical advantage (IMA) of a lever
IMA equals length of effort arm divided by length of resistance arm.
A grooved wheel with a rope, simple chain, or cable running along the groove. A modified first-class lever.
A fixed pulley
Attached to something that doesn't move; force is not multiplied but direction is changed; IMA = 1
A moveable pulley
has one end of the rope fixed and the wheel free to move; multiplies force; IMA = 2.
Block tackle system of pulleys
consisting of fixed and moveable pullleys; IMA = number of ropes supporting resistance weight.
IMA of Inclined Plance
length of slope (effort distance) divided by height of slope (resistance distance)