4*4 Newton’s Law of Universal Gravitation: The Ups and Downs of a Roller Coaster WDYS??? (p382) MOON VS. JUPITER WDYT??? Gravity (does/does not) have magnitude and direction, therefore it is a (scalar/vector) quantity. Since Earth is spherical, the direction of gravity __________ will be different in different places, like Australia.

4*4 Investigate 1a) A penny drops in the _____ direction. 1b) The penny ALWAYS accelerates toward the center of Earth at 9.8m/s/s (OR 10m/s/s)!!! 1c) Gravitational Field is _____. 1d) Draw a “falling map” for Earth. 1h) The force of gravity is (strong/weak).

4*4 Investigate 2a) Make an (a-d) graph from data on p384 2b) As the distance from Earth’s surface increases, the acceleration due to gravity _____.

The change in acceleration is an 4*4 Investigate 2c) What is the acceleration at the following distances? i) 10,000km =4m/s/s ii) 20,000km = 1m/s/s iii) 30,000km =0.44m/s/s iv) 40,000km = 0.25m/s/s 2d) What is the ratio of acceleration at the following distances? i) 20,000km : 10,000km= ii) 30,000km : 10,000km= iii) 40,000km : 10,000km= The change in acceleration is an INVERSE-SQUARE RULE

The change in acceleration is an 4*4 Investigate 2c) What is the acceleration at the following distances? i) 10,000km =4m/s/s ii) 20,000km = 1m/s/s iii) 30,000km =0.44m/s/s iv) 40,000km = 0.25m/s/s 2d) What is the ratio of acceleration at the following distances? i) 20,000km : 10,000km= 1 : 4 = 1/4 ii) 30,000km : 10,000km= 0.44 : 4 = 1/9 iii) 40,000km : 10,000km= 0.25 : 4 = 1/16 The change in acceleration is an INVERSE-SQUARE RULE

4*4 Investigate INVERSE-SQUARE RULE  When distance is DOUBLED (×2), the acceleration becomes ¼ its original value When distance is TRIPLED (×3), the acceleration becomes 1/9 its original value When distance is QUADRUPLED (×4), the acceleration becomes _____ When distance is ×5, the acceleration becomes _____

4*4 Investigate INVERSE-SQUARE RULE  FGravity = 1 d2

Physics Talk (p385): Newton’s Law of Universal Gravitation Earth’s Gravitational Field is EVERYWHERE!!! 1st object (Earth) = source of the field 2nd object (Penny) = the response/test object Gravitational Lines  Direction of force on mass toward center of Earth Acceleration due to gravity is greater closer to Earth, weaker as you move farther away They are everywhere and beyond!!!

Physics Talk (p385): Newton’s Law of Universal Gravitation 2. The Inverse-Square Relationship The force of gravity between two objects decreases by the square of the distance between them EXAMPLE If distance is tripled (×3), then the force is 1/32 or 1/9 the original force As an object moves AWAY from Earth, the force of gravity DECREASES drastically!!!

Physics Talk (p385): Newton’s Law of Universal Gravitation Universal Gravitation  all objects have MASS and Earth attracts ALL objects EXAMPLE an apple falls from a tree the Moon in outer space Gravity  the force of attraction between two bodies due to their masses ***The force of gravity is quite weak/small***

Physics Talk (p385): Newton’s Law of Universal Gravitation ALL bodies with MASS attract all other bodies with MASS The force of gravity is DIRECTLY proportional to the 2 masses EXAMPLE larger the mass, stronger the gravity smaller the mass, weaker the gravity c) The force of gravity is INVERSELY related to the distance between the 2 masses EXAMPLE closer the distance, stronger the gravity greater the distance, weaker the gravity

Checking Up (p387) The direction of the gravitational field in the classroom is _____. The gravitational field is strongest where the lines are _____. If you triple the distance between masses, the force becomes _____ the strength of the original force. The force of _____ holds the Moon in orbit around Earth. The shape of the orbits of the planets around the Sun is approximately an _____.

PTG (p390) 1. If the distance is doubled, the force will be reduced by _____, therefore it will be ___N. 2a) Doubling the distance would reduce the force by a factor of 1/22, so the force would be _____. 2b) Tripling the distance would reduce the force by a factor of _____. 2c) Increasing the distance by a factor of 4 would reduce the force by a factor of _____.

PTG (p390) 4. The force of gravity at the top and bottom of a roller-coaster ride is essentially _____. 5a) _____ is closer to the Moon. 5b) Because the water is closer, it has a slightly _____ force of gravity acting on it.

PTG (p390) 7. Since force of gravity = 1/ distance2, the force would be _____. a) b) c) d) 8. Since force of gravity = mass × mass, the force would be _____. a) b) c) d)

4*4 TOTD Acceleration due to gravity is greater __________, weaker as you move __________. The equation for the INVERSE-SQUARE LAW is _____. If the force between 2 objects is 500N and the distance is ×5, the new force becomes _____. The 2 factors that effect gravity are _____ and _____. Draw the Earth’s Gravity Lines 