Section 3: Gravitational Freefall

Intro Video Black Holes: https://www.youtube.com/watch?v=e-P5IFTqB98

Scientist Who Pioneered the Concept of Gravity Galileo:15 February 1564[4] – 8 January 1642),[1][5] commonly known as Galileo, was an Italian physicist, mathematician, astronomer and philosopher who played a major role in the Scientific Revolution Found that all object fall at the same rate by rolling balls of different masses down ramps. Supported the idea that the Earth moves around the sun.

Sir Isaac Newton: (25 December 1642 – 20 March 1727 [NS: 4 January 1643 – 31 March 1727])[1] was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian. Derived the equation that shows the attritional force between objects. Newtons Universal Law of Gravitation

Albert Einstein:14 March 1879 – 18 April 1955) was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. 1) Developed general theory of relativity stating that gravity is the result of two objects masses distorting time and space to create an attraction. (Relativity Video on file)

Properties of Gravitational Fields Gravitational fields are proportional to the mass of the planet. Double the planets mass and so does its gravitational field.

2) Gravitational fields grow much stronger as you get closer to the planet. (if the distance decreases by half the attraction force increases by _____ times)

3) Gravitational fields extend extremely long distances even across and between entire galaxies.

4) All objects will fall at the same gravitational acceleration if there is no air friction.

Finding Earth’s Gravity:

Freefall of objects Dropped: Galileo dropped a cannon ball from the Tower of Pisa. Find the speed and distance for each second in time:

Freefall for a Vertical Launch: A cannon ball is shot directly in the air. Find the velocity and displacement for each second of travel.

Sample Problem: Find ball is thrown vertically upwards at a rate of 44 m/s. 1) Draw a picture of the situation: 2) Find the time for the ball to reach the maximum height: 3) Find the maximum height: 4) Find the velocity of the ball after 6.5 seconds.

Applied Sample Problem: A rock it dropped from a cliff. 1) Find the velocity of the rock after 15 seconds. 2)Find how far the rock dropped.

Warm-up: A cliff jumper on a far away planet jumps off a cliff Warm-up: A cliff jumper on a far away planet jumps off a cliff. Find the velocity and location for each second of freefall. Velocity Distance Bonus: Find how long it will take him to hit the ground if the cliff is 1000 meters high.

Warm-up: A bomb is dropped from a plane a height of 2000 meters. Find the following: 1) How long for the bomb to hit the ground. 2) How fast the bomb is traveling. a = ΔV/t

Freefall video on file: http://www.youtube.com/watch?v=Qw8OJJQ_hgk&feature=related http://www.youtube.com/watch?v=sQw_C5KLhFM&feature=related&safety_mode=true&persist_safety_mode=1&safe=active http://www.youtube.com/watch?v=bQ0Ha2p8GjI&feature=related&safety_mode=true&persist_safety_mode=1&safe=active

Quiz: 12 pts Find the velocity after dropping for 20 seconds. Find how far he drops after 20 seconds: If the cliff is 400m high, how long will it take to hit the ground:

Quiz: 20 pts If Joe Kittinger jump from a height of 102,800 ft, find the following: How long it would take him to hit the ground if there was no air friction. His final velocity: