gravity homework

Assume that air resistance is negligible in these problems.

1.  Consider a baseball dropped from a height of 8-m. 
a.  How long should it take to hit the ground?
b.  What speed will it have immediately before impact with the Earth?

2.  You drop a rock from a bridge.  It takes 1.5 seconds to reach the water below.  How high above the water is the bridge?

3.  You throw a baseball straight up into the air with an initial speed of 25 m/s.
a.  How long does it take to reach apogee (highest point)?
b.  How high does it rise?
c.  How long would it spend in air before returning to your hand?

This one is trickier.  This is where it is important to consider signs and direction.  I suggest that you assign UP as the direction POSITIVE (which makes down negative). 

Three more related problems for this one:

d.  What would a graph of distance vs. time look like for this entire problem (up and down)?  Again, I suggest that you consider up to be positive.
e.  What would a graph of velocity vs. time look like for this problem?
f.  What would a graph of acceleration vs. time look like for this problem?

HW reminder

Hey folks. Just a reminder for homework:

Calculate the accelerations from your lab (informal) data. Get an average of all values.

Also, if you have time, think about these questions:

1. Should everyone get the same answer?

2. How does gravity change as your altitude increases?

3. How might gravity change as you go beneath the surface of the earth?

4. What would gravity be like at the center of the earth?

Motion homework

1. What do you notice is different about the 4(or 5) equations of motion?

2. Consider a car that goes from 0 to 30 m/s over a distance of 20 m.
A. What is the acceleration?
B. How long did this take?
C. What would a graph of distance vs. time look like for this scenario?
D. What would a graph of velocity vs. time
Look like for this scenario?

3. What is the acceleration due to gravity (g)? What does it represent?