Simple Machines, Work, and Mechanical Advantage

units of force are

• newtons

• grams

• joules

• meters

units for work are

• newtons

• joules

• meters

• seconds

if you push a cart with a force of 60 N for 2 m... how much work have you done

• 120 J

• 30 J

• 120 N

• 30 N

work transfers

• sweat
• energy
• velocity
• effort

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Which situation is work not done?

• lifting a 20 pound box off the floor
• holding a 20 pound box above the floor
• sliding a 20 pound box across the floor
• sliding a 20 pound box up an inclined plane

Which is doing work?

• pushing a wall
• holding a box
• picking up a pencil
• sitting in a chair

A machine with a 5-N input force and a 25-N output force has a mechanical advantage of?

• 2

• 5

• 20

• 125

No machine can be 100% efficient because of

• Thermal energy

• Waste energy

• Convection energy

• Friction

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The doorknob is an example of a simple machine known as a __________________, that makes work easier by using ___________________ to multiply a force.

• wedge, direction

• wheel and axle, distance

• wheel and axle, direction

• pulley, distance

The efficiency of a machine can be increased by reducing __________________________. 

• effort
• resistance friction
• fulcrum
• friction