PHYSICS 50: Lecture 11.1 RICHARD CRAIG. Homework #11 Chapter 12 We will skip 12.8 12.3, 12.13,...
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Transcript of PHYSICS 50: Lecture 11.1 RICHARD CRAIG. Homework #11 Chapter 12 We will skip 12.8 12.3, 12.13,...
PHYSICS 50: Lecture 11.1
RICHARD CRAIG
Homework #11 Chapter 12
We will skip 12.8 12.3, 12.13, 12.23, 12.54, 12.55 Due Tuesday April 22
Today Force of Gravity
Examples Acceleration due to gravity Gravitational Potential energy
Escape velocity Circular Orbits
Examples
Newton’s Law of Gravitation There is a force of attraction between
any two masses F = Gm1m2/R2
G is a universal constant G = 6.67 x 10-11Nm2/kg2
Newton’s Law of Gravitation
Examples Me and you
Me and earth
Three particles
Calculate gravitational variables
To add forces due to multiple masses you must add vectors
Weight (skip Weight Watchers, just climb upward) Gravity (and hence, weight) decreases as altitude rises.
Things that effect your “weight” Altitude Latitude “Local” variations in rocks
Barometric pressure
Gravitational force changes densities below sea level• Just as it’s interesting to
remember that all gravitational forces are calculated from the center of the planet, it’s interesting to follow the density as one proceeds from crust to mantle to core.
• “Want to get away”? Consider Example 12.4 to calculate gravity on Mars.
Gravitational potential energy
Objects changing their distance from earth are also changing their potential energy with respect to earth.
If an object has enough kinetic energy to overcome the gravitational potential energy it can escape from the gravitational pull
1/2 mv2 > GmM/R
Escape Velocity
Satellite motion
Consider satellite orbits
Circular Orbit Examples Low Earth Orbit (LEO) Geosynchronous orbit Moon