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Physics: Motion, Energy & Heat Unit II(b) – Hagebusch NEO A&M General Physical Science – PHYS 1014
Physics:Motion, Energy & Heat
Unit II(b) – Hagebusch
NEO A&M
General Physical Science – PHYS 1014
Work
• Work – _______________________________ __________________________________________________________________________
work = _______ x ________W = Fd
• ___________ – the SI base unit of measurement for work
Work
• Example 3.1– How much work is needed
to lift a 5.0 kg backpack to a shelf 1.0 m above the floor?
• Example 3.2• How much work is required
to lift a 50 lb box vertically a distance of 2.5 ft?
Power
• Power – ______________________________ _____________________________________
power = P =
• Power is measured in units of ___________• 1 hp = 550 ft∙lb/s• 1 hp = 746 W (watts)
Power
W t
P
Power
• Example 3.3– An electric lift can raise a
500.0 kg mass a distance of 10.0 m in 5.0 s. What is the power of the lift?
• Example 3.4• A 150 lb person runs up a 15
ft stairway in 10.0 s. What is the horsepower rating of the person?
Potential Energy
• Energy – ______________________________
• ____________________ – energy associated with an object position– measured in joules ( J )
gravitational potential energy = ________ x ________PE =
Potential Energy
• Example 3.5– What is the potential
energy of a 2.14 kg book that is on a bookshelf 1.0 m above the floor?
• Example 3.2• How much work can a 5.00
kg mass do if it is 5.00 m above the ground?
Kinetic Energy
• Kinetic energy – ________________________ _____________________________________
– Ways to measure kinetic energy
1. The work _____________________________________
2. The work _____________________________________
• measured in joules ( J )
kinetic energy =KE =
Kinetic Energy
• Example 3.7
– A 7.00 kg bowling ball is moving in a bowling lane with a velocity of 5.00 m/s. What is the kinetic energy of the ball.
• Example 3.8
– A 100.0 kg football player moving with a velocity of 6.0 m/s tackles a stationary quarterback. How much work was done on the quarterback?
Energy Flow
Resistance
1. Work against _________
2. Work against _________
3. Work against _________
4. Work against _________
5. Work against _________
Energy changes
1. Increased ___________
2. Increased ___________
3. Increased ___________
4. Increased ___________
Energy Forms
• _____________________– the form of energy associated with machines, objects in motion, and objects having potential energy due to gravity– Ex: ______________________________________
• ______________________– energy stored in the chemical bonds between atoms– Released in a reaction know as ______________
– Ex: ______________________________________
Energy Forms
• _____________________–the energy that travels through space
– ______________________– all forms of radiant energy that travels in the form of a wave
Energy Forms
• __________________________– form of energy from electromagnetic interactions
• __________________________– form of energy derived from interactions of the nucleus of atoms
Energy Conversion
Energy Conversion
• Potential energy can be converted to kinetic energy
Example 3.9• A 1.0 kg book falls from a height of 1.0 m. What is the velocity of the
book just as it hits the floor?
Example 3.10• What is the kinetic energy of a 1.0 kg book just before it hits the floor
after a 1.0 m fall?
Energy Conservation
• ____________________________________
– Energy is neither created nor destroyed. Energy can be converted from one for to another, but the total energy remains constant.
Common Energy Sources
• Fossil Fuels
– Petroleum
– Coal
• Moving Water
• Nuclear
• Solar
• Wind
• Geothermal
Energy Conservation
• U.S. Energy Information Administration– The total primary energy use per capita in the
United States in 2003 was almost identical to that in 1973
– Economic output (gross domestic product GDP) increased 74%
– National energy intensity (energy used per unit of GDP) fell 43%
– The energy savings was an estimated $430 billion to consumers
