Exercises

Exercise

How much energy does the average person in the United States use each year?

Strategy

• Find a figure for US energy use

• Find a figure for the US population

• Checking units says to divide the two

Exercise

The world uses 474 EJ of energy per year. How much is that per person per year?

Strategy

• Find global energy use

• Find global population

• Divide

Exercise

What is the average power that each US person consumes?

Strategy

• Use the definitions of power and energy with what we know about US

  energy usage per year

Exercise

We calculated that each American on average consumes 300 GJ of energy each year.

How many barrels of oil would provide that amount of energy?

Strategy

• How much energy is in a barrel of oil

Exercise

How many kilograms of coal would provide that energy?

Strategy

Exercise

What is the volume of this much coal?

Multiplication of efficiencies

• When we want to know the efficiency of a process with many steps, we

  multiply the efficiencies at each step to get the total.

  $\eta_{total} = \eta_1 \cdot \eta_2 \cdot \eta_3 \cdots$

Exercise

How much energy does the average person in the United States use each year?

Strategy

• Find a figure for US energy use

• Find a figure for the US population

• Checking units says to divide the two

Exercise

The world uses 474 EJ of energy per year. How much is that per person per year?

Strategy

• Find global energy use

• Find global population

• Divide

Exercise

What is the average power that each US person consumes?

Strategy

• Use the definitions of power and energy with what we know about US

  energy usage per year

Exercise

We calculated that each American on average consumes 300 GJ of energy each year.

How many barrels of oil would provide that amount of energy?

Strategy

• How much energy is in a barrel of oil

Exercise

How many kilograms of coal would provide that energy?

Strategy

Exercise

What is the volume of this much coal?

Exercise

The world uses 474 EJ of energy per year. How much is that per person per year?

Strategy

• Find global energy use

• Find global population

• Divide

Exercise

What is the average power that each US person consumes?

Strategy

• Use the definitions of power and energy with what we know about US

  energy usage per year

Exercise

We calculated that each American on average consumes 300 GJ of energy each year.

How many barrels of oil would provide that amount of energy?

Strategy

• How much energy is in a barrel of oil

Exercise

How many kilograms of coal would provide that energy?

Strategy

Exercise

What is the volume of this much coal?

Exercise

How much energy does the average person in the United States use each year?

Strategy

• Find a figure for US energy use

• Find a figure for the US population

• Checking units says to divide the two