November 8

AP Physics

Homework:

25, 26,27,28

Each group presents their problem

In:

If the moon has a mass of 7.347 7 × 1022 kg, an orbital speed of 1.022 km/s an orbital radius of 384 399 km, What is the gravitational force of the earth moon system?

Objective:

To find out about the law of universal gravitation.

Success criteria:

You will be able to solve universal gravitational problems.

Newton’s Law of Universal Gravitation

Newton’s Law of Universal Gravitation:

Problem:

Oscar (mass=65kg) and Olivia (mass=45 kg) sit 2 meters apart in physics class. What is the force of gravitational attraction between them? Does this cause them to drift toward each other?

Gravitational force is a vector

Inverse square laws

Anything that spreads out from a point source

– Gravitational force– Electrical force– Sound intensity– Light intensity– Radiation intensity

Inverse square law - gravitation

Inverse square law – light intensity

Light intensity

Inverse square law - radiation

Inverse square law – electric force

Sound spreads out as an inverse square

For the rest of class:

1-Gravitational problem set2-Lab: centripetal force

• Finish the calculations

• Analysis

• Conclusion due at the end of class.

Out:

If the distance between two point particles is doubled, then the gravitational force between them:

a) Decreases by a factor of 4b) Decreases by a factor of 2c) Increases by a factor of 2d) Increases by a factor of 4e) Cannot be determined without knowing

the masses.

A rubber stopper goes in a circle with a string of radius 2 meters. The string is inclined at 40o from vertical. The stopper has a mass of .3 kg. The string has a tension of 10 N. How fast is the stopper going?