the product of force and distance when force is used to move an object
unit of work, the SI unit of energy
a device that changes the amount of force exerted or the direction in which force is exerted
the force exerted on a machine
the force applied by a machine
the number of times the force exerted on a machine is multiplied by the machine
the percentage of the input work that is converted to output work
actual mechanical advantage
the mechanical advantage that a machine provides in a real situation
ideal mechanical advantage
the mechanical advantage that a machine would have without friction
a simple machine consisting of a flat surface with one end higher than the other
a simple machine consisting of a device that is thick at one end and tapers to a thin edge at the other
a simple machine that consists of an inclined plane wrapped around a central cylinder to form a spiral
a simple machine consisting of a rigid object that pivots about a fixed point
the fixed point around which a lever pivots
wheel and axle
a simple machine consisting of two circular objects that are fastened together and rotate about a common axis
a simple machine consisting of a grooved wheel around which is wrapped a rope, chain, or cable
a device that combines two or more simple machines
two or more wheels linked together by interlocking teeth
machine with no friction
Simple machines do not multiply energy
W(out) is never > W(in)
A watt is equal to __________
one newton per second
A transfer of energy when a force makes an object move in the same direction (Joules)
The rate or amount of work being done in one second (Watts)
how many times a machine multiplies a force
input compared to output
machine that has only 1 movment
combination of simple machines
The Force-Distance Trade-off
Machines often will increase the distance of the object has to move, but the input effort force is decreased. The same amount of work is done.
the force applied to a machine
the force applied by the machine to overcome resistance is called
work done by you on the machine
work done by the machine
The Ideal Machine
Input work = Output work (not possible due to friction)
the number of times a machine multiplies the effort force
less than one
When MA is ____ ____ ___, the machine increases the distance moved or the speed
When the MA is ______ ___, the machine changes the direction of the Fe.
greater than one
When the MA is _______ ____ ___, the machine increases the Fe.
High efficiency machines
produce less heat from friction
W out / W in x 100%
You can make machines more efficient with ___ ______.
a machine that does work with only one movement
barsthat are free to pivot or turn about a fixed point called a fulcrum
the distance from the fulcrum to where the resistance force is applied
When you double the distance, you can ____ the force
the distance from the fulcrum to where the effort force is applied
first class lever
used to multiply the force and change the direction of the applied force (screwdriver opening a paint can)
second class lever
the resistance froce is located between the effort force and the fulcrum; multiplies force (wheelbarrow)
the length of the arm / length of the resistance arm
a grooved wheel with a rope, chain, or cable running along the groove
a modified first class lever that can multiply force and/or change the direction of the applied force; attatched to something that does not move
one end of the rope is fixed and the wheel is free to move; it multiplies force by increasing the distance you pull
block and tackle pulley
a system of pulleys made of fixed and moveable pulleys; can have large mechanical advantages
wheel and axle
a machine made up of two wheels of different sizes that rotate together (doorknoibs, pencil sharpener)
the effort force is usually exerted on the
the smaller wheel is the
two or more interlocking wheels that may change the direction of the force
sloping surfaces that reduce the amount of force required to do work by increasing the distance over which the force is applied
length of slope / height of slope
For inclined planes, the IMA =
As a ramp/inclined plane is made longer and less steep, ____ _____ is required.
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