Lecture 19 Satellites

Quick Review Newton’s Law of gravity

Circular Orbits M is mass of parent and m the mass of the satellite. M>>m Kepler’s Law

Geostationary Satellite At the equator, how far above the earth’s surface should a satellite orbit so it stays overhead? R earth = 6.37 x 10 6 m G=6.67 x Nm 2 /kg 2 M earth = 5.98 x kg

A cyclist goes around a level, circular track at constant speed. Since the cyclist’s speed is constant, her acceleration is constant 1.True 2.False

QUIZ A motor cycle is in a loop-the-loop. At the top of the loop… A) Draw a free body diagram B) What is the minimum speed the motor cycle must have if the radius of the loop is 15. m?

Homework due Friday Problems: 6: 24, 25, 27, 29, 33, 44, 45, 51, 58, 59

Problem 6:27 What is the ratio between the sun’s gravitational force on you and the earth’s gravitational force on you? R earth = 6.37 x 10 6 m G=6.67 x 1011 Nm 2 /kg 2 M earth = 5.98 x kg R earth-sun =1.5 x m M sun = 1.99x10 30 kg

Problem 6:27 cont Take ratio

6:33 The space shuttle is in an orbit 250 miles high. What are its orbital period (in minutes) and orbital speed? R earth = 6.37 x 10 6 m G=6.67 x Nm 2 /kg 2 M earth = 5.98 x kg 1 mi = km

6: mi *1.609km/mi=326.5 km r= 6.37 x 10 6 m x 10 5 m =6.70 x 10 6 T=5.46 x 10 3 s = 90.9 minutes

6:44 A 5g coin is placed 15cm from the center of a turntable. µs = 0.80, µk = As turntable starts from rest and speeds up to 60 rpm, does coin slide off?

So coin does not slip

T W=mg r=0.20m 1.0m θ 6:45 Conical Pendulum Find T, ω

6:51 Ultracentrifuge R=0.10 m 70,000 rpm Δm= 10 mg = kg What is net force? r a

6:58 Martian geostationary satellite What are its speed and altitude? dayMars:=24.8 hours

6:59 g on Mars, Maximum walking speed?