Find the gravitational attraction of the moon to the Earth using the regents reference tables.

What would the gravitational attraction of the Earth to the moon be?

What if the moon where twice as massive?

Gravity

Find the gravitational attraction of the moon to the Earth using the regents reference tables.

What would the gravitational attraction of the Earth to the moon be?

What if the moon where twice as massive?

Gravity

F = G x M1 x M2 / r2

= (6.67 E-11) x (7.35 E22) x (6.37 E24)

(3.84 E8)2

= 2 billion billion Newtons

What happens to a person’s weight at an altitude of 1 earth radii?

Find the attraction of a 50 kg satellite at 1 earth radius above the earth.

Find the gravitational attraction between these two masses?

Find the gravitational attraction between an electron and a proton in a hydrogen atom ( r = 10-6 m ).

Henry Cavendish’s experiment to measure G .

How is gravity involved in creating the tides?

M

Find the total gravitational force on the 30 kg sphere due to the other 2 spheres.

To achieve orbit, you must launch a rocket at a certain minimum velocity, called the orbital velocity, where the object’s weight can provide the centripetal force, and the earths curvature makes up for the objects falling.

Fc = W

r

vescape = gr

mv2 = mg

The “force field” model:

A drawing wher arrows represent the direction oif the force on an object. The denser the lines, the stronger the field and the stronger the force

Fg

m g =

g = 9.8 g = 6 g = 2.5

g = 9.81 N/kg

G is relatively constant at 9.81 N/kg near the surface of the earth.

Sensitive gravimetric measurements show variation of g at different points on earth’s surface at the 5th decimal place

Gravitational Map of New England

Why is the gravity stronger over oceans?

VERY exaggerated graphics of where g is strongest and weakest on earth’s surface, due mainly to variances in local rock densities.

A 50 kg mass experiences a weight of 1,000 Newtons on planet X. Find the gravitational field strength on planet X.

What is the acceleration of gravity on planet X?

LAW 2: Planets sweep out equal areas in equal intervals of time

LAW 3: The squares of the periods of the planets are proportional to the cubes of their distance to sun:

Ta2 / Tb

2 = Ra3 / Rb

3

LAW 1: The orbit of a planet is an ellipse with the Sun's center of mass at one focus

Kepler’s Laws of Motion

Ta2 / Tb

2 = Ra3 / Rb

3

Planet Period

“T” (yr)

a (AU)

T2 R3

Mercury 0.24 0.39

Venus 0.62 0.72

Earth 1.00 1.00

Mars 1.88 1.52

Jupiter 11.9 5.20

Saturn 29.5 9.54

Neptune is 30 times further from the sun than we are. Calculate its period of orbit.

Neptune is 30 times further from the sun than we are. Calculate its period of orbit.

Neptune is 30 times further than we are from the sun. Calculate its period of orbit.

In another solar system, planet X is 5 times farther away from its central star than planet Y. Planet X has a solar year of 500 days. Find the period of planet Y.