Chapter 9

Chapter 9Tuesday, March 31, 2020 11:01 AM

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Chapter 9 - Work and Kinetic Energy

Chapter 9 - Work and Kinetic EnergyTuesday, March 31, 2020 11:03 AM

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ch09_work_kinetic_energy

Clicker QuestionsTuesday, March 31, 2020 11:06 AM

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Chapter 9: Work and Kinetic EnergyScalar Product DefinitionTuesday, March 17, 2020 10:38 AM

Scalar Product 1 Page 34

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Tuesday, March 17, 202011:51 AM

Problem 9.15Evaluate the dot product of the three pairs of vectors in the figure below.

Scalar Product 2Tuesday, March 17, 2020 11:39 AM

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Problem 9.11Evaluate the dot product

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Definitions we care about:

Energy: that property of an object or system that enables it to do work

Work: to exert a force over a displacement

System: a defined collection of objects to be studied

Environment: everything that is not part of the system

Internal Forces: forces that objects within the system exert on other objects within the system

External Forces: forces that the environment exert on the system

Energy OverviewMonday, March 30, 2020 10:41 AM

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Forms of energy we will be dealing with:

Kinetic Energy (K or KE): energy of motion

Gravitational Potential Energy (Ug): energy an object has in an elevated position

Elastic or Spring Potential Energy: energy stored in a stretched or compressed spring

Thermal Energy (Eth): heat - sum of kinetic and potential energies of all the atoms and molecules in an object or system

Chemical Energy (Echem): energy stored in the bonds between atoms and molecules

Types of EnergyMonday, March 30, 2020 10:44 AM

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Work Done by Gravity

Wednesday, April 1, 2020 10:30 PM

Intro to spring Page 42

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April 7 Tuesday, April 7, 2020 10:58 AM

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Tuesday, April 7, 2020 11:36 AM

Preview of what's left Page 47

Tuesday, April 7, 2020 11:46 AM

Thermal Energy Page 48

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Tuesday, April 7, 2020 12:00 PM

Power Page 50

Chapter 9 REcapTuesday, April 7, 2020 4:19 PM

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Example Problems 9.10, 9.33 (2 ways), and 9.28

Problem 9.10

The cable of a crane is lifting a 750 kg girder. The girder increases its speed from 0.25 m/s to 0.75 m/s in a distance of 3.5 m. (a) How much work is done by gravity? (b) How much work is done by tension?

Problem 9.33

A baggage handler throws a 15 kg suitcase along the floor of an airplane luggage compartment with a speed of 1.2 m/s. The suitcase slides 2.0 m before stopping. Use work and energy to find the suitcase’s coefficient of kinetic friction on the floor.

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Problem 9.28

A 60 kg student is standing atop a spring in an elevator as it accelerates upwards at 3.0 m/s2. The spring constant is 2500 N/m. By how much is the spring compressed?

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