Energy Efficiency

Efficiency is calculated by useful energy output divided by total energy input, expressed as a percentage

• False

• True

What is the efficiency of a machine if 55.3 J is inputted, but only 14.3 J is produced?

• 0.25 Joules

• 26%

• 3.86 Joules

• 386%

Total energy = 200J
Useful energy = 20J

Workout the efficiency of this lightbulb.
 $efficiency\ =\ \frac{energy\ out}{energy\ in}\ \times100$  

• 100%

• 80%

• 40%

• 10%

Total energy = 350J
Useful energy = 70J

Workout the efficiency of this iphoneX.
 $efficiency\ =\ \frac{energy\ out}{energy\ in}\ \times100\%$  

• 100%

• 80%

• 40%

• 20%

Total energy = 3400J
Useful energy = 340J

Workout the efficiency of this vintage VW Beetle.
 $efficiency\ =\ \frac{energy\ out}{total\ energy\ in}\ \times100\%$  

• 100%

• 10%

• 40%

• 20%

This car needs 8600J of energy to power it. If 5000J is changed into useful energy, how much energy is wasted?

• 13600J

• 3600J

• 5000J

• 8600J

Tags

NGSS.MS-PS3-1

NGSS.MS-PS3-5

A car transfers 100 J of chemical energy in order to gain 50 J of kinetic energy. The efficiency of the car is

• 20%

• 0.5%

• 50%

• 200%

What is the work output of a machine that has a work input of 2,800 Joules and an efficiency of 92.3%? 

• 2,690J
• 92.3J
• 0.0082J
• 2,584.4

Tags

NGSS.HS-PS3-1

What is the useful work output of a machine that consumes 2,800 Joules and an efficiency of 40%?

• 7000 J

• 2760 J

• 1120 J

If an appliance is 85% efficient and outputs 340 J, what is the input energy?

• 740J

• 60J

• 340J

• 400J