Mechanical Advantage and Efficiency

A force of 50 N is applied to the end of a lever to lift a rock that is 350 N.  What is the MA of the lever?

• 70

• 0.14

• 7

• 17,500

A pulley is used to raise a heavy crate. The pulley is such that an input force of 223 N is needed to provide an output force of 1784 N. What is the mechanical advantage of this pulley?

• 8

• 0.125

• 397,832

• 1561

A knife has a slope of 3 centimeters and the width is 1.5 centimeters, what is the mechanical advantage of this wedge?

• 2

• 0.5

• 3

• 4.5

Tags

NGSS.MS-PS2-2

A machine has a work output of 8 joules and requires 10 joules of work input to operate. What is the machine's efficiency?

• 8 J

• 10 J

• 80%

• 800%

What is the efficiency of a machine that has work input of 40 joules and work output of 35 joules?

• 87.50%

• 1200

• 1.142

• 114%

Jeff is a landscaping contractor and lifts a rock weighing 600 pounds by wedging a board under the rock. Jeff weighs 150 pounds and puts all of his weight on the lever. How much mechanical advantage did the lever provide to Jeff in lifting the rock?

• 0

• 2

• 4

• 8

Tags

NGSS.MS-PS3-5

A lever and fulcrum are used to lift a fallen tree, which has a weight of 480 N. If the lever has a mechanical advantage of 5.5, what is the input force that will begin lifting the tree off the ground?

• 5.5 N

• 40.7 N

• 87.3 N

• 2640 N

Tags

NGSS.MS-PS2-2

This device

• wedge

• lever

• incline plane

• wheel and axle

What is the efficiency of the machine if the input is 263 J and the output is 142 J?

• 6.26%

• 54%

• 100%

• 260%

the percentage of the input work that is converted to output work

• mechanical advantage

• efficiency

• joule

• machine