Final Exam schedule has been published… PHYS 214: Saturday May 8th at 10:20 am-12:20 pm Room 112, Physics

RQ9: The gravitational force exerted by the Earth on the Moon is much larger than the gravitational force exerted by the Moon on the Earth, which is why the Moon revolves around the Earth. A. True B. False

Lecture Quiz: On a Ferris Wheel, when is the NORMAL force on you largest? A.At the top B.At the bottom C.At the sides D.It must be constant E.Its magnitude must always equal gravity.

Ferris Wheel AT REST There is no acceleration, so no net force on the riders. Weight is exactly cancelled by the Normal force from the seat. W W W W N N N N N + W = 0 = ma

N top N bottom Ferris Wheel IN MOTION Circular acceleration a = v 2 /r Centripetal force = mv 2 /r, always directed inward. Weight is constant; Normal force varies.

Lecture Quiz: Question 1 What happens if the speed v gets so large that the centripetal acceleration equals g? (a=v 2 /r = g) A.The normal force at the top disappears (N=0), and you feel “weightless”. B.The normal force at the bottom disappears (N=0), and you feel extra heavy. C.The normal force exactly equals your weight. N top N bottom

Fig Is the Moon falling?

When viewed from earth the other planets are observed to move forward then backwards then forward again in their motion against the fixed stars. This is know as: a) geocentric view b) retrograde motion c) ptolemy’s Law d) Heliocentric e) Kepler’ 3rd law

Which of the following did not have a theory of Planetary Motion? 1. Ptolemy 2. Copernicus 3. Tyco Brahe 4. Kepler 5. Newton

Which is not one of Kepler’s Laws The planets move in elliptical orbits about the sun, with the sun at one focus of the ellipse. A planet will make one retrograde motion every epicyle. The radius vector drawn from the sun sweeps out equal areas in equal times. T 2 /R 3 is constand for all the planets.

Tides are strongest at The earth’s north pole The earth’s south pole Along the earth’s equator At the middle latitudes ( near Lafayette) The same everywhere on earth

Tides are strongest when 1.When the sun and moon are on opposite sides of the earth 2.When the sun is directly overhead 3.When the moon is directly overhead 4.When the sun and moon are directly overhead 5.Tides are not effected by the sun or the moon

The tides occur Two high tides every ~25 hours One high tides every day at Noon 2 Low tides for every 5 high tides Two high tides every month Two high tides every 48 hours