Gravitational Interactions

Can you name a few ways gravity affects things on our planet?? Newton Again Sir Isaac Newton did not discover gravity. He discovered that gravity is universal All matter attracts all other matter. Can you name a few ways gravity affects things on our planet??

Have you ever heard of a force field? A force field surrounds things with mass. We call it a gravitational field.

Remember this picture…

What is your acceleration as you fall? a=9.8m/s2 a=4.9m/s2 a=0m/s2 a=4.9m/s2 a=9.8m/s2

Your weight would be zero! What would your weight be if you were in a cavity at the center of the Earth? Your weight would be zero!

Imagine a journey to the center of the Earth Imagine a journey to the center of the Earth! What motion would you experience?

Weight & Weightlessness What would a scale read (higher or lower than normal) if your were on an elevator: Accelerating up? Higher! Accelerating down? Lower! In freefall after the cable breaks? Zero!

Weight & Weightlessness Weightlessness is not the absence of gravity. It is the absence of a support force.

Why do astronauts feel weightless?

Why do astronauts feel weightless? If you had a ladder that could reach as high as a shuttle's orbit, your weight would be 11% less at the top. A person who weighs 100 pounds on the Earth's surface would weigh about 89 pounds at the top of the ladder. The astronaut, the spaceship and everything inside it are falling towards the Earth (weightless). They are always falling towards the Earth, but they never get there.

MICROGRAVITY The further an object is away from another object, the force of gravity is weaker. The further an object moves from the surface of the Earth, the less gravity it feels from the Earth. Scientists on the Space Shuttle experience microgravity

MASS WEIGHT Mass and Weight are two different Properties of Matter Mass is a physical property of matter that explains how much matter is in an object Mass does not change when gravity changes WEIGHT Weight is a force which is calculated by multiplying the acceleration of gravity times mass. Weight can change when gravity changes

Reference Point A point or standard used for comparison

OCEAN TIDES What causes them?

OCEAN TIDES Low Tide High Tide High Tide Low Tide Why are there two per day? Because the Earth spins under this bulge!

Largest and smallest tides Neap tide- sun is at 90 degrees relative to Earth and moon, tide is smallest Spring tide- Sun, Moon, and Earth are all Aligned, tide is largest.

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