Efficiency of Machines

Ratio to work out to work in

• Efficiency
• Law of Conservation of Energy
• Transformation
• Lumens

What is the efficiency of a machine when the input is 263 J and the output is 142 J. {Eff = Work out/Work in) x100}

• 1.85 %

• 18.5 %

• 5.39 %

• 53.9 %

Tags

NGSS.MS-PS3-5

The law of conservation of energy states that when one form of energy is converted into another,

• energy is destroyed in the process
• no energy is destroyed in the process
• energy is created in the process
• some amount of energy cannot be accounted for

Tags

NGSS.MS-PS3-1

NGSS.MS-PS3-5

What is the efficiency of a machine if 55.3 J of work are done on the machine, but only 14.3 J is produced by the machine? {Eff = Work out/Work in) x100}

• 0.25 J

• 26%

• 386%

• 3.86 J

What is the efficiency of the machine if the input is 263 J and the output is 142 J? {Eff = Work out/Work in) x100}

• 6.26%

• 54%

• 100%

• 260%

What is the efficiency of a machine that has work input of 40 joules and work output of 35 joules? {Eff = Work out/Work in) x100}

• 87.50%

• 1200

• 1.142

• 114%

Lucas has been challenged to increase the efficiency of a device he is redesigning. His goal is 90% efficiency. The work input of the device is fixed at 10 joules, so Lucas is trying to improve work output. How many joules of work output should Lucas aim for to attain his goal of 90% efficiency? {Eff = Work out/Work in) x100}

• 9 Joules

• 900 Joules

• 0.9 Joules

• 25

Tags

NGSS.MS-PS3-5

A machine has a work output of 8 joules and requires 10 joules of work input to operate. What is the machine's efficiency? {Eff = Work out/Work in) x100}

• 8 J

• 10 J

• 80%

• 800%

What is the work output of a machine that has a work input of 2,800 Joules and an efficiency of 92.3%? {Eff = Work out/Work in) x100}

• 2,690J

• 92.3J

• 0.0082J

• 2,584.4

Work output of a large machine in a factory is 89,000 Joules, and its input is 102,000 joules. Work output of a similar machine is 92,000 joules, and its work input is 104,000 joules. Which machine has greater efficiency? {Eff = Work out/Work in) x100}

• The first machine

• The second machine

• Not enough information provided