# cueFlash

## Glossary of Bob Jones science 9 chapter work and machines

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In science, work is accomplished when...
a force acts on an object as it moves through a distance.
14A
Formula for work...
w=f x d

14A
a newton-meter is also a...
joule (which is also kg x m2
_______
s2 )
14A
Things that make work easier that have only one or two parts...
simple machines
14A
Machines can do these 3 things, but never this...
can do: increase the amount of force, change the direction of force, and change speed of force
can't do: increase the amount of work done or energy expended 14A
a bar that turns on a point...
lever. The point is the fulcrum. 14A
Law of Moments...
w1d1 =w2d2
14A
In first class lever, where is the fulcrum?
between the effort on one end and the resistance on the other
14A
Force multiplying ability...
14A
ratio of resisting force /applied force
or ratio of distance effort applied/distance resistance moves 14A
In a second class lever, the resistance is...
between the effort on one end and the fulcrum on the other.
14A
In a third class lever, the resistance is...
on one end, the effort in the middle, and the fulcrum on the other end. 14A
Name the class of these levers: wheelbarrow, biceps, seesaw.
second, third, first
14A
This modified lever overcomes the limited distance that a resistance can be moved with a lever...
wheel and axle
14B
A single fixed pulley doesn't give you any mechanical advantage but it does...
change the direction of force.
14B
A single moveable pulley gives you an advantage of...
2 (but the rope must be pulled twice as far as the weight rises)
14B
An arrangement of fixed and moveable pulleys...
block and tackle
14B
To find the mechanical advantage in a block and tackle...
count the number of ropes supporting the resistance.
14B
Distance principle...
any reduction in the effort force will be paid for by an increased distance through with the force must act 14B
Inclined planes reduce the ...
effort to raise a load 14B
The mechanical advantage of an inclined plane...
length of incline/height
Two inclined planes placed bottom to bottom...
wedge
An inclined plane wrapped around a cylinder...
screw
pitch. (also defined as the distance it moves inward for each turn it is given)
A machine's actual performance (or ratio of work output to work input)...
its efficiency
Rate of doing work...
Power
Power formula...
work/time
Units for power...
watts (W)