Work and Simple Machines

How is the energy of an object affected after work is done on it?

• Energy is increased

• Energy is decreased

• Energy remains the same

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NGSS.MS-PS3-4

NGSS.MS-PS3-5

Which machine works by changing the direction of a force?

• A rake

• A pulley

• A screwdriver

Which statement describes the relationship between input work and output work?

• Input work = output work

• Input work less than input work

• Input work is always greater than output work

Answer explanation

Output work is always less than the input work because some input work is used to overcome friction.

All machines make work easier, but they don't increase the amount of work that is done.

The ratio of output work to the input work

• Power

• Efficiency

• Work

• Mechanical advantage

The rate at which work is done

• Power

• Efficiency

• Work

• Mechanical advantage

Tags

NGSS.MS-PS3-5

A simple machine made of a grooved wheel with a rope or cable wrapped around it

• Pulley

• Screw

• Wedge

• Inclined plane

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NGSS.MS-PS2-1

NGSS.MS-PS2-2

A sloped surface that moves

• Pulley

• Screw

• Wedge

• Inclined plane

An inclined plane wrapped around a cylinder

• Pulley

• Screw

• Wedge

• Inclined plane

A flat, sloped surface

• Pulley

• Screw

• Wedge

• Inclined plane

Why is efficiency always less than 100%?

• There is always some friction which takes away from 100%

• Because a machine is always stronger than a human

• Because machines make things go slower.

Tags

NGSS.MS-PS3-5