Lecture 5 - Racquetball Striking a Wall Copyright: Loren M....

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Physics 140: Winter 2008 Lecture #5 January 17, 2008 Dr. Dave Winn Racquetball Striking a Wall Copyright: Loren M. Winters Mt. Etna Andrew Davidhazy
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Dynamics: what do we need to explain? How and why do things change? First great realization: what constitutes change? Old and incorrect idea : anything not sitting still needs to be explained, motion has to have a cause Not a surprising notion: To keep something moving you need to keep pushing: motion implies a mover
Background image of page 2
Galileo reveals another illusion… In free fall, Galileo saw that air friction was a complication: worked to remove it To understand other motions, friction must be removed as well What does motion without friction look like?
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Newton’s first law Any body continues in a state of rest, or of uniform motion in a straight line, unless it is compelled to change its motion by forces imposed on it. Newton’s first law defines inertial reference frames. In an inertial frame objects move at constant velocity unless a force acts on them. In a non-inertial (accelerating frame) objects appear to change velocity in the absence of applied force. Also called the “law of inertia”: tendency to remain the same FORCES change motion
Background image of page 4
A car travels around a curve at a constant speed. Is there a net force acting on it? 1. No, its speed is constant 2. Yes 3. It depends on the speed of the car and the sharpness of the curve Any time the velocity changes there must be unbalanced forces acting
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 19

Lecture 5 - Racquetball Striking a Wall Copyright: Loren M....

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online