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. TrueB. 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

WW

N

N

N

N

N + W = 0 = ma

Ntop

Nbottom

Ferris Wheel IN MOTION

Circular acceleration

a = v2/r

Centripetal force = mv2/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=v2/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.

Ntop

Nbottom

Fig. 5.17

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 viewb) retrograde motionc) ptolemy’s Lawd) Heliocentrice) Kepler’ 3rd law

Which of the following did not have a theory of Planetary Motion?

1. Ptolemy2. Copernicus3. Tyco Brahe4. Kepler5. 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.

• T2/R3 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 overhead3. When the moon is directly overhead4. When the sun and moon are directly

overhead5. 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