Nature of Energy Practice Problems
A round chocolate cake is divided into 8 slices and has the following data:
Calories per round chocolate cake = 1600 Cal
How many Calories are in one slice of chocolate cake?
A 40-g serving of oatmeal contains 27 Calories, of which 20% is derived from fat. Calculate your caloric intake from fat if you consume 100 g of oatmeal.
The human heart produces 4680 J of energy in an hour. Assume that this energy can be used to light a fluorescent lamp. For how many minutes, is this energy sufficient to light a 25 W fluorescent lamp? (1 W = 1 J/s)
The amount of heat needed to increase 1.0 lb of water's temperature by 1.0 °F is measured in British thermal unit (BTU). A Quad is 1015 BTU. How many joules are in a Quad?
The average annual electricity consumption of a household in Florida is 1141.50 kWh per month. Assuming that a solar panel has a 15.5% efficiency and light from the sun supplies 168 W of energy per square meter, calculate the area (m2) of land that must be covered in order to achieve the average household need per month. [Assume 1 month has 30 days]
Light from the sun supplies 168 W per square meter. Calculate the mass of water that can be evaporated from a 2.50 square meter portion of a pond for a period of 8.0 hours. Assume that water evaporates due to the energy supplied by the sun. (ΔHvap H2O = 40.67 kJ/mol)
About 0.9 kg of CO2 is produced per day per human. Assume that all of this CO2 comes from the metabolism of glucose as shown in the following reaction:
C6H12O6(s) + 6 O2(g) → 6 CO2(g) + 6 H2O(l) ΔH = –2803 kJ/mol
About 75% of the energy generated is used for daily basic functions and 25% is used to maintain electric potential in cellular functions. Calculate the energy generated for daily basic functions in kW based on the CO2 produced per day.
Your potential energy increases as you climb up the stairs. You use energy from the metabolism of food to increase your potential energy. What energy is being converted to potential energy?
A typical infrared lamp emits 175 watts of energy. Calculate the total energy emitted in kcal by the infrared lamp after 12 hours. (1 watt = 1 J/s)
One type of cookie contains 53% carbohydrate, 43% fat, and 4% protein. Determine the percent of the calorie content of this cookie that is carbohydrate.