Apply Newton’s law of universal gravitation to solve problems. Explain how Newton’s Law of Universal Gravitation accounts for various phenomena.

Three people of equal mass are located in different locations. Person 1 is on the top of a mountain, person 2 is at sea level, and person 3 is in the bottom of a canyon. Who weighs the most? Why?

Gravitational force is the mutual force of attraction between particles of matter. All objects exert a gravitational force of attraction on one another. Why are you not all clumped together in the middle of the floor?

Gravitational force depends on the masses and on the distance between them. The constant G, called the constant of universal gravitation, equals  10 –11 Nm 2 /kg.

Find the magnitude of the gravitational force a 66.5kg person would experience while standing on the surface of each of the following planets: a) Earth – mass=5.97x10 24 kg; r=6.38x10 6 m Ans: 636N a) Mars – mass=6.42x10 23 kg; r=3.40x10 6 m b) Ans: 241N c) Pluto – mass=1.25x10 22 kg; r=1.20x10 6 m d) Ans: 37.6N

Earth ( m = 5.97  kg) orbits the sun ( m = 1.99  kg) at a mean distance of 1.50  m. What is the gravitational force of the sun on Earth? ( G =  Nm 2 /kg 2 ) F  N G  N H  10 –2 N J  10 –8 N

Use your known weight to calculate acceleration due to gravity. Mass of Earth=5.97x10 24 kg Radius of Earth= 6.38x10 6 m Feather and a Bowling Ball...Which will hit first?

A 60kg person stands at sea level then drives to a mountain 1000km above sea level. Compare the weight of the person at both places. Mass of Earth=5.97x10 24 kg Radius of Earth= 6.38x10 6 m

Find the distance between a.300kg pool ball and a.400kg pool ball if the magnitude of the gravitational force between them is 8.92x N. Ans:.300m

A student with no physics brain took a dive off the high dive and hit the water with their body flat and face down (belly flop). Why did it hurt so badly? NOTE: A physics rock star would not do this.

For every action force, there is an equal and opposite reaction force that is equal in magnitude and opposite in direction. …in other words…Forces come in pairs! They do NOT cancel, and DO act on different objects. Ex: rocket launch tennis gravitation

 The gravitational forces that two masses exert on each other are always equal in magnitude and opposite in direction.  This is an example of Newton’s third law of motion.  One example is the Earth-moon system, shown on the next slide.

If a 2kg ball falls towards Earth from a height of 5m, it accelerates at what rate? Does the Earth accelerate towards the ball? How would you prove this? Mass of Earth=5.97x10 24 kg Radius of Earth= 6.38x10 6 m

What causes ocean tides? Draw a diagram to enhance your answer.

When are the tides the largest (Spring tide) and the smallest (Neap tide)? Draw a diagram to enhance your explanation. pring-neap.jpg 1.jpg

 As a result of these forces, the moon and Earth each orbit the center of mass of the Earth-moon system. Because Earth has a much greater mass than the moon, this center of mass lies within Earth.