Lecture 4 - PHYSICS 220 Lecture 04 Forces and Motion in 1 D...

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January 24, 2011 Physics 220: Lecture 4 1 Lecture 04 Forces and Motion in 1 D Textbook Sections 3.2-3.6 PHYSICS 220
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Objectives • Understand the difference between mass and weight • Recognize the relationship between forces and interactions • Investigate frictional forces • Analyze objects in free-fall • Quantify the movements and forces in pulley, strings, and cable. January 24, 2011 Physics 220: Lecture 4 2
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Mass and Weight • In everyday language the terms mass and weight are used interchangeably They are not the same! • Inertial mass is an intrinsic property of matter – It is a measure of an object’s resistance to changing its motion when a force is applied – Does a satellite in space have mass? January 24, 2011 Physics 220: Lecture 4 3 F = m a An astronaut is working on two satellites in space, one twice the mass as the other. He has to move them, would each take the same force to move with the same acceleration?
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Mass and Weight • Passive gravitational mass is a measure of an object’s reaction to a gravitational field • Active gravitational mass measures the strength of the gravitational field generated by an object • Weight, W , is the product of the object’s mass and the local gravitational acceleration January 24, 2011 Physics 220: Lecture 4 4 W = m g Our astronaut is now on the moon. Is her weight the same on the moon as it is on Earth? What about her mass?
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January 24, 2011 Physics 220: Lecture 4 5 Forces and interactions • Definition of force – an influence that causes an object to accelerate • Our view of the universe is that there are 4 different forces that drive the interactions between objects – Gravitation – Electromagnetism – Weak interaction – Strong interaction • These forces act through the empty void of space – action at a distance
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January 24, 2011 Physics 220: Lecture 4 6 Contact Forces Contact force: a force between two objects that are in contact with each other
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This note was uploaded on 04/10/2011 for the course PHYS 220 taught by Professor Chang during the Spring '09 term at Purdue University-West Lafayette.

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Lecture 4 - PHYSICS 220 Lecture 04 Forces and Motion in 1 D...

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