Mechanical Efficiency

The more supporting strings a pulley system has, the less efficient it is because ___________________.

• there is more friction

• its harder to lift the load

• there is more weight

• you are changing the direction of the force

Tags

NGSS.MS-ETS1-1

An assembly line machine needs 150 J of input work to do 90 J of output work. What is the efficiency of the machine?

• 167%

• .6%

• 60%

• 1.67%

What happens to the overall efficiency of a machine as I add more machines?

• For each simple machine you add, the overall efficiency increases because it gets faster.

• For each simple machine you add, the overall efficiency decreases.

• The overall efficiency is divided in half for every simple machine you add.

• There is no connection.

What is the efficiency of this compound machine if the efficiencies for each machine is as follows: lever= 95%, wheel and axle= 90%, and wedge = 80%?

• 68%

• 100%

• 6.84%

• 265%

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%

Efficiency is calculated by dividing the ________ by the ________ and multiplying by 100.

• work output/input

• force output/input

• Fxd

• work input/output

What is mechanical efficiency?

• The ratio of work output to work input, expressed as a percentage

• The amount of energy lost due to friction

• The speed at which a machine operates

• The total energy consumed by a machine

Tags

NGSS.MS-PS3-4

NGSS.MS-PS3-5

A machine has an input work of 200 J and an output work of 150 J. What is its mechanical efficiency?

• 75%

• 150%

• 133%

• 50%

Which factor does NOT affect the mechanical efficiency of a machine?

• Friction

• Air resistance

• The color of the machine

• The design of the machine