Sustainable Energy
2nd Edition
ISBN: 9781337551663
Author: DUNLAP, Richard A.
Publisher: Cengage,
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Chapter 1, Problem 7P
To determine
Find the monetary value of the person per day.
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4. The human heart pumps the average adult's 6.0 liters (6000 cm3) of blood
through the body every minute. The heart must do work to overcome frictional
forces that resist blood flow. The average blood pressure is 1.3x104 N/m²
a) How much work does the heart do to move the 6.0 liters of blood completely
through the body?
b) What power output must the have to do this task once a minute?
Hint: When the heart contracts, it applies a force to the blood. Pressure is
force/area. Model the circulatory system as a single closed tube, with crosssectional
area A and volume V=6.0 liters, filled with blood to which the heart applies
a force.
Determine the mass of a person climbing a tree 5 meters high in 9 seconds with power of 450 joule.
Problem 10
A homeowner is trying to decide between a high-efficiency natural gas furnace with an efficiency of 95
percent and a ground-source heat pump with a COP of 3.3. The unit costs of electricity and natural gas are
$0.112/kWh and $1.44/therm (1 therm = 105, 500 kJ). Determine which system will have a lower energy
cost.
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Sustainable Energy
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- What is the best definition for non- renewable energy? O a. It is energy collected by humans that can be replaced after five to ten years. O b. It is energy from finite sources that cannot be replaced by natural means at a quick pace of time. O c. It is energy from finite sources that can be replaced after using them. O d. It can be measured in joules or kilowatts.arrow_forwardQ5. Hydropower generation is responsible for a large percentage of power generation world- wide.arrow_forwardReplacing incandescent lights with energy-efficient fluorescent lights can reduce the lighting energy consumption to one-fourth of what it was before. The energy consumed by the lamps is eventually converted to heat, and thus switching to energy-efficient lighting also reduces the cooling load in summer but increases the heating load in winter. Consider a building that is heated by a natural gas furnace with an efficiency of 80 percent and cooled by an air conditioner with a COP of 3.5. If electricity costs $0.12/kWh and natural gas costs $1.40/therm (1 therm = 105,500 kJ), determine if efficient lighting will increase or decrease the total energy cost of the building (a) in summer and (b) in winter.arrow_forward
- Q2 A dam is used to store 700 tons of water to provide energy when needed by using turbines. If the water is stored at a height of 60 meters above ground level, calculate how much energy is stored if the water was to be released to ground level. Provide and analyse two alternative methods of energy storage.arrow_forward1) Heating the water in a 55-gallon water heater requires about 2.0 x 103 kJ of energy. a) Assume the energy came from natural gas with 80% efficiency; how many grams of natural gas are required? b) Assume the energy came from electricity with 80% efficiency and that the electricity was produced from the combustion of coal with 30% efficiency; how many grams of coal are required? For problem above, calculate how much CO2 in grams is emitted to the atmosphere. For a: Use the balanced equation for the combustion of methane (CH4) to determine how many grams of CO2are produced from the amount of natural gas required. For b: Assume that coal produces 5.25 kJ of energy per gram of CO2 produced. Calculate how much CO2 in grams is produced.arrow_forwardA certain brand of hotdog cooker works by applying a potential difference of 146 V across opposite ends of a hot dog and allowing it to cook by means of the thermal energy produced. The current is 12.8 A, and the energy required to cook one hot dog is 60.8 kJ. If the rate at which energy is supplied is unchanged, how long will it take to cook three hot dogs simultaneously? Number i Unitsarrow_forward
- A centrifugal pump is driven by a motor. The performance of the pump reveals the following information:Power input to the pump by the motor (kW):0.5, 0.7, 0.9, 1.0, 1.2Power input to the fluid by the pump (kW):0.3, 0.55, 0.7, 0.9, 1.0Plot the efficiency curve. The efficiency of a pump is a function of the flow rate. Assume that the flow-rate readings corresponding to power data points are equally spaced.arrow_forwardIf the overall efficiency of the system and turbine in the figure is 80 percent, what horsepower is Ans: 18,152 hp produced for H=200ft and Q=1000cfs? 10ft diaarrow_forwardA turbine generates the power of 150,000 kW while working at the speed of 300 rpm at the head of 100 m. What is the specific speed of the turbine?arrow_forward
- An average American consumes approximately 105 kJ of energy per day. The average life expectancy of an American is 77.9 years. How much coal would need to be burned to provide enough energy to meet a person's energy demands if the efficiency of energy production from coal is 38%? ☐g coalarrow_forward2. Consider the system described in the news: at night, when there is energy left, water is pumped from a large lake to a reservoir at 80 m above the lake level. During the day, this water is used to generate energy in a turbine located 80 m below the elevated reservoir. Considering that the water flow is always 5000 liters/s (both at the inlet of the reservoir and at the outlet) and that the pump and turbine efficiencies are 70%, what is the power (in kW) required by the pump and the power (in kW) recovered in the turbine. Data: The pipe diameter is always the same along the system (d = 0.5 m); g = 10 m/s2; γ = 9810 N/m3. Matter transport phenomena; Please make it typeable as handwriting interferes with understandingarrow_forwardWork done by an engine in 6 sec is 1000 joules. What is the power generated by the engine in watt? a. 1600 watt b. 600 watt c. 166 watt d. 600 wattarrow_forward
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