Calculating Energy Requirements for Human Activity on Inclined Surfaces

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In summary, the question discusses the energy requirements of an average human and how to calculate the height of a hill with a 12 degree incline to consume all of that energy. The formula Eg=mgh is mentioned, but it is clarified that h refers to just the vertical displacement. The role of gravity is also discussed in relation to work done and potential energy. It is noted that energy is a scalar quantity, not a vector.
  • #1
thegame
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here is a question that I am unable to solve:

The average human, of mass 52 kg needs to have approximately 9,000,000 J of energy per day. Suppose, you had to walk up a hill with an incline of 12 degrees. Determine the following:
a) how high would the hill have to be (i.e. - change in height) in order to consume all of this energy.
b) how much work did gravity do in all of this walking?

for A, i know you have to use the formula Eg=mgh but i am not sure where to sub in the energy as 9,000,000J or sin 12*9,000,000 (since its at an angle)

B) i don't knoe what role gravity plays in this?
 
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  • #2
In the formula mgh, h refers to just the vertical displacement, not the total distance.

For the work, you need to consider the definition of work done by a force (in this case, gravity) -- or, equivalently (in this case), the work done by changing potential energy.
 
  • #3


Originally posted by Ambitwistor
In the formula mgh, h refers to just the vertical displacement, not the total distance.

sorry, but you haven't answered my question? directly
 
  • #4


Originally posted by thegame
sorry, but you haven't answered my question? directly

Energy is energy. You don't multiply it by anything.
 
  • #5
SO, energy is not a vector quantity?
 
  • #6
No, energy is a scalar.
 

1. What is energy and how is it measured?

Energy is the ability to do work. It is measured in joules (J) or kilowatt-hours (kWh). Joules are used to measure small amounts of energy, while kilowatt-hours are used for larger amounts, such as the energy used in a household.

2. What are the different types of energy?

The main types of energy are kinetic, potential, thermal, chemical, nuclear, and electromagnetic. Kinetic energy is the energy of motion, potential energy is stored energy, thermal energy is the energy of heat, chemical energy is stored in bonds between atoms, nuclear energy is stored in the nucleus of an atom, and electromagnetic energy is energy that travels in waves.

3. How is energy converted from one form to another?

Energy can be converted from one form to another through various processes such as mechanical work, electrical work, and heat transfer. For example, a wind turbine converts mechanical energy from the wind into electrical energy, and a stove converts electrical energy into thermal energy to cook food.

4. What are the sources of energy?

The main sources of energy are fossil fuels, nuclear power, and renewable sources such as solar, wind, hydro, and geothermal energy. Fossil fuels, such as coal, oil, and gas, are non-renewable sources of energy that are formed from the remains of plants and animals. Nuclear power uses the energy from splitting atoms to generate electricity.

5. How does energy impact the environment?

The production and consumption of energy can have both positive and negative impacts on the environment. Fossil fuels contribute to air and water pollution, as well as greenhouse gas emissions and climate change. Renewable energy sources have a lower environmental impact, but their production and installation can also have some negative effects on the environment. It is important to find ways to use energy more efficiently and shift towards cleaner, renewable sources of energy to reduce our impact on the environment.

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