Chapter 6:Circular motion and Gravitation

Work out the radial acceleration of the moon around the earth.

Ferris wheel

Conical Pendulum Center-seeking Force: Tension Circular Motion

Conical Pendulum

No Skidding on a Curve (I) Center-seeking Force : Static Friction msmin = ?

No Skidding on a Curve (II) r = 50.0 m C m = 1000 kg v = 14.0 m/s

No Skidding on Banked Curve arad +

6-54.When the system rotates about the rod the strings are extended as shown. The tension in the upper string is 80 N

6-55 . As the bus rounds a flat curve at constant speed, a package suspended from the luggage rack on a string makes an angle with the vertical as shown.

Gravitation Newton’s Law of Gravitation

Gravitational attraction Note: Two particles of different mass exert equally strong gravitational force on each other

Gravitational Forces (I) MM MM ME FG = G r 2 ‘‘Attractive Force” ME

Why is the Aggie not falling off the earth? Remember there is equally strong attraction between the earth and the Aggie and vice versa

Cavendish balance Cavendish(1798) announced that he has weighted the earth

Average Density of the Earth g = 9.80 m/s2 RE = 6.37 x 106 m ME = 5.96 x 1024 kg rE = 5.50 x 103 kg/m3 = 5.50 g/cm3 ~ 2 x rRock

Projectile

Circular orbit The larger r then slower the speed and the larger the period

Work and Energy

Black hole Steven Hawkins is associated with the department of Physics and Astronomy at TAMU

(will be derived later) How can the sun become a Black Hole? r This would increase the sun’s mass. There is a second way: Decrease sun radius