### Physics

##### concept reinforcement quiz 2
Free Fall according to Galileo

Section 1: Development of the theory:

1. Compare the method Galileo used to convince his readers with other styles of writing.   [Hint: Most books of Galileo's day were written in the style of Euclid's Geometry.]

2. Galileo defined acceleration as....

3. A football is kicked straight upwards.   Compare its ACCELERATION [both magnitude AND direction]
1. just after being kicked, while it is going up,
2. at the instant it reaches its greatest height, and
3. while coming down, just before it is caught.

4. Derive Galileo's famous equation, d = 1/2 at2 from basic equations and assumptions.

5. What are the limiting conditions on Galileo's equation: d = 1/2 at2?

6. No team obtained results from Galileo's Lab (Experiment I-2: Free Fall) in perfect agreement with Galileo's equation.   Discuss if this proves Galileo wrong.   Explain.

7. What were Galileo’s beliefs on motion?   How were they different from Aristitle’s?   What did Galileo do to convince himself that his ideas were correct?

8. Why did Galileo NOT directly test his theory of falling objects?

9. In what time period did Galileo live?

10. What is the numerical value of the acceleration of a falling object near the surface of the earth?

11. What is Galileo's principle of relativity?

Section 2: Mathematical section: Apply your understanding by making specific predictions. List all equations you use, and show substitutions and algebra.   Show your stepwise solution procedure.  Answers need to be reported with the correct uncertainty (i.e., the correct number of significant figures), and appropriate unit labels:

1. A ballast sand bag is dropped from a hot air balloon.   Ignoring friction as insignificant, and presuming the balloon is high enough so the bag has not hit the ground, how fast would you expect the bag to be travelling 5.0 seconds after release?

2. What will be the bag's average speed for the first 5.0 seconds after release?

3. What distance will the bag transverse in those 5.0 seconds after release?

4. A gun is fired STRAIGHT UPWARDS with an initial bullet speed of 100 m/sec.   How long will it take for the bullet to reach its highest position and stop rising?

5. What will be the maximum altitude attained by the bullet?

6. Presuming friction is insignificant, what will be the bullet's speed 5.0 seconds after fired?

7. How long a time will it take the bullet to rise and return to the ground?