Universal Gravitation, Vertical Throw and Satellites
One law explains a falling apple, a ball tossed in the air and the Moon in the sky.
Big Idea: Every body in the Universe attracts every other body. Newton's law of universal gravitation gives the size of that pull. Near the Earth's surface this same pull is what we call gravity, it gives every falling body the acceleration g, and it is strong enough to hold the Moon and artificial satellites in their orbits.
By the end of this topic you will be able to:
- state the law of universal gravitation and use F = G·m1m2/r2;
- explain why free fall gives every body the same acceleration g;
- describe and calculate the motion of a body thrown straight up or down;
- explain how an artificial satellite stays in orbit and estimate the first cosmic velocity.