Wednesday we will look at one of the many reasons objects may accelerate, the force of gravity. We'll start with notes on what we know and don't know about gravity, and some **really simple** applications of a gravity equation.
Then we'll jump to solving for the amount of gravitational acceleration. This one gets a bit tricky, but it comes out that all objects accelerate toward the Earth at the same rate. The proof of this will come with Newton's 2nd law (Friday/Monday maybe).
After some lab-exercises analyzing and solving for "g" which is known as acceleration due to gravity, we'll look at sample problems involving "g" in place of "a" and find out some cool answers to acceleration problems for objects accelerated by gravity.
Tomorrow's homework (due Thursday): Read p. 104-105, and solve the following:
Explain your answers OR show work.
1a. How long will it take a ball dropped from a height of 2m to reach the ground?
b. How fast will the ball be moving when it hits the ground?
2. A rock is thrown upward at 30 m/s (about 70 mph) by a FHS geology student. How fast will it be moving after: a. 2 seconds? b. 3 seconds? c. 4 seconds?
3a. A penny is dropped off a building. Find its velocity 2.5 seconds later.
b. At the same time, a second penny was pushed off by a broom, moving horizontally at 2 m/s. Draw a picture relating the motions of these two pennies during the first 2.5 seconds of their fall from the same height.
BONUS: If the FHS geology student catches the rock, how fast will it be going, and how long was the rock in the air?
A cool video to check out relating to in-class activities and discussion:
http://dsc.discovery.com/videos/mythbusters-dropped-vs-fired-bullet.html
Or just look up on youtube: Mythbusters dropped vs fired bullet
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