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Ch 14 Work Power SM

Work, Power, and Simple Machines

QuestionAnswer
A grooved wheel with a rope, chain, or cable running along the groove. Pulley
An inclined plane with one or two sloping sides. It is used for prying or cutting. Wedge
A bar that is free to pivot or turn around a fixed point. Lever
A shaft or axle attached to the center of a larger wheel, so that the wheel and axle rotate together. Wheel and Axle
A sloping surface, such as a ramp that reduces the amount of force required. It is usually used for lifting up. Inclined Plane
A cylindrical shape with an inclined plane wrapped around it. Screw
Give an example of a compound machine. Scissors, bicycle, etc. Anything that has 2 or more simple machines
What class of lever is a broom? When you sweep with it the pivot is your shoulder, you push in the middle, and work is done at the end. Third Class lever
What class of lever are scissors? First Class Lever
What class of lever is a wheel barrow? Second Class Lever
What is the mechanical advantage of a machine? It tells how much a machine multiplies your force. It is the ratio of output force/input force, or input distance/output distance.
How do simple machines make work seem easier? They change the force needed by the person using them, but NOT the work done. They can also change the distance, speed, or direction
A device that does work with only one motion simple machine
A device that is made up of two or more simple machines compound machine
A push or pull Force
Force x distance Work
An object must do this for work to be done MOVE in the direction of the force
The rate of doing work, or work/time Power
SI Unit for Force Newton (N)
SI unit for Work Joule (J)
SI unit for Power Watt (W)
Si unit for time second (s)
SI unit for distance meter (m)
How are work and energy related it takes energy to do work
What is horsepower the power of an average strong horse, English unit of power.
The work a person does on a machine by moving it input work
the work a machine does on something else output work
Do machines do more work that the person does using them NO. Output work is always a little smaller due to energy lost as heat or friction. They just make work seem easier by changing the force, distance, speed, or direction of work.
The force a person pushes on a machine with input force
The force a machine pushes on something else with output force
The distance a person moves a machine input distance
The distance a machine moves something else output force
Do machines make less work? NO! They make it seem easier by changing: force, distance, direction, or speed. But the work done is the same.
Name the simple machine or machines in a wheel barrel 2nd class lever and wheel and axle
Name the simple machine or machines in a screw driver to pry open a paint can 1st class lever and wedge
Name the simple machine or machines in a pair of scissors 1st class lever and wedge
Name the simple machine or machines in a bike wheel and axle (pedals, gears, and wheels), levers in kick stand, brakes, handle bars for steering
Name the simple machine or machines in a flag pole or miniblinds pulley
Name the simple machine or machines in a steak knife wedge
Name the simple machine or machines in a soda bottle screw (lid)
Name the simple machine or machines in a hammer wedge, first class lever pulling out a nail, third class lever hammering in a nail
Name the simple machine or machines in a winding trail with switch backs (zig zag path) up a mountain inclined plane
Name the simple machine or machines in a pencil sharpener wheel and axle and wedges inside for sharpening the pencil
Name the simple machine or machines in a nut cracker wedges and 2nd class lever (pivot on end, nut in middle, and you pull on other end)
Name the simple machine or machines in a staple remover wedges and 3rd class lever (pivot on end, you push in the middle, and staples removed at other end)
What is the work done move a box 3 meters with 50 N of force 150 Nm or 150 J
What is the power required to move a box 3 m with 50 N of force if it takes 3 sec 50 J/s or 50 W
What is the IMA of a lever with an input arm of 11 cm and an output arm of 2 cm 5.5 (no unit!)
What is the AMA of a machine that has an input force of 50 N that produces an output force of 350 N? 7
What is the efficiency of a machine that does 800 J of output work with 850 J of input work? 94%