Chapter 9 - Gravity

Question 1

What did the Newtonian Synthesis do?

Answer 1

It compared the fall of an apple with the “fall” of the moon.
It stated that the moon falls away from the straight line it would follow if there were no forces acting on it.

Question 2

What is the Law of Universal Gravitation?

Answer 2

For any pair of objects, each attracts the other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

Question 3

What is the equation(s) for the Law of Universal Gravitation?

Answer 3

F ~ (mass1 x mass2)/distance^2
F = G(mass1 x mass2)/distance^2

Question 4

What is the Universal Gravitational Constant (G)?

Answer 4

G = 6.67 * 10^-11 N*m^2/kg^2.

Question 5

Is gravity a weak or strong force compared to the fundamental forces?

Answer 5

Gravity is the weakest of the four fundamental forces.

Question 6

What does Weight depend on?

Answer 6

Mass & distance from Earth’s CENTER.

Question 7

What is the Inverse-Square Law?

Answer 7

The intensity of an effect is inversely proportional to the square of the distance from the source.

Question 8

What is the definition of Weight?

Answer 8

Weight is the force that an object exerts on a supporting surface. This is often due to the force of gravity.

Question 9

What is Weightlessness?

Answer 9

Weightlessness is a condition where an object has no support force, but there is still a gravitational force causing downward acceleration.

Think of astronauts!

Question 10

What are Ocean Tides caused by?

Answer 10

Ocean tides are caused by the differences in the gravitational pull between the moon and the earth on opposite sides of Earth.

Question 11

What are Spring Tides?

Answer 11

Spring tides are high/low tides that occur when the Sun, Earth, and the Moon are all lined up so the tides are higher/lower than average.

Question 12

What are Neap Tides?

Answer 12

Neap tides are tides that occur when the Moon is half between a new/full moon. The Sun/Moon tides partially cancel.

Question 13

How long does the Moon take to make one revolution?

Answer 13

27.3 days.

Question 14

The Moon rotates ____ bulges & Earth rotates ___ bulges.

Answer 14

The moon rotates with bulges & Earth rotates beneath bulges.

Question 15

Can Tides occur in ponds? Why?

Answer 15

No! No part of a pond is closer or further to the Moon/Sun than any other part.

Question 16

What is Gravitational Field?

Answer 16

A gravitational field is a force field that exists in the space around every mass.

Question 17

What is the gravitational field at the Earth’s center?

Answer 17

Gravitational field = 0 at Earth’s center.

Question 18

Is Acceleration minimized or maximized at the Earth’s center? What about Velocity?

Answer 18

Acceleration is minimum; velocity is maximum.

Question 19

What is a Black Hole?

Answer 19

A black hole is a concentration of mass that results from gravitational collapse. Here, gravity is so intense that not even light can escape.

Question 20

Why is the Earth round?

Answer 20

Because of gravity! It has attracted itself into itself and become a sphere.