Lecture 8: Wed, Sep 20, 2023
Lab with Engineer Anas
Lecture 9: Mon, Sep 25, 2023
Assignment 2:
Submission deadline: Friday, October 6th, 2023, 11:59 PM
Notes:
- Please submit typed assignment. Plagiarism will be checked for submitted assignments.
- All the diagrams and figures must be hand-made (sketched with hand on paper and then scan and insert in report)
- Submission accepted via Black Board only.
- Approximate number of typed pages: 7-10 pages
- Define and briefly explain the following concepts in your own words.
• Define & briefly explain: Fourier's law of conduction, Newton’s law of cooling, Stefan-Boltzmann law
• Name some good conductors of heat; some poor conductors.
• What is the order of magnitude of thermal conductivity for (a) metals (b) solid insulating materials, (c)
liquids (d) gases?
• What is the meaning of thermal resistance
• Define and briefly explain Thermal Diffusivity
• Mach number
• Law of conservation of momentum
FORMS OF ENERGY
Force is an interaction that can change the state of an object.
Work is the endurance of force over a distance.
where 𝑊 is the work, 𝐹 is the applied force, and ∆𝑑 is the distance.
Energy is a measure of the ability of the object to do something.
• The object can convert work delivered to it into another form of useful energy.
• Energy is conserved → as much of energy you give as you will receive.
• Work is a form of energy.
Power is the endurance of the energy over a period of time.
Power = Energy/ Time
FORMS OF ENERGY
Different Forms of Energy
2. Elastic Energy (Ue)
It is a stored energy in an elastic material or spring. This energy is used to return
the material or the spring to its original size.
𝑈𝑒 =
1
𝑘𝑠 2
2
(J=N.m) or (Ib.ft)
where
𝑘 is the spring constant (or stiffness) (N/m) or (Ib/ft).
𝑠 is the stretch or compression in the spring (m) or (ft).
FORMS OF ENERGY
Different Forms of Energy
3. Kinetic Energy (Uk)
It is the energy that generate due to objects
motion.
1
𝑈𝑘 = 𝑚𝑣2
2
(J=N.m) or (Ib.ft)
where
𝑚 is the mass of the object (kg) or (slug).
𝑣 is the object velocity (𝑚/𝑠) or (𝑓𝑡/𝑠).
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FORMS OF ENERGY
Different Forms of Energy
4. Heat (Q)
Heat is a form of energy that make atoms of the material move to increase
materials temperature.
When an amount of heat is silvered to a material, the material temperature
increases such that:
where
𝑚 is the mass of the object (kg) or (slug).
𝑐 is the object’s specific heat (J/𝑘𝑔℃) or (Ib. 𝑓𝑡/slug℉).
𝑇 − 𝑇0 is the temperature rise due to the added heat.
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Practice example:
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Example:
Note: Heat supplied by air is equal to the heat absorbed by water
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CONSERVATION OF ENERGY
Conservation of Energy
The energy required to move an object between two positions is conserved.
𝑈𝑔1 + 𝑈𝑒1 + 𝑈𝑘1 = 𝑈𝑔2 + 𝑈𝑒2 + 𝑈𝑘2
Kinetic Energy at Position 1
Elastic Potential Energy at Position 1
Gravitational Potential Energy at Position 1
Kinetic Energy at Position 2
Elastic Potential Energy at Position 2
Gravitational Potential Energy at Position 2
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