Physics Problems 1

Woo Hoo – it’s physics problems with motion! OH YEAH!!!

Questions from the first 2 classes:

1. What are the SI standards for mass, length and time?

2. What are these standards CURRENTLY based on?

3. What is evidence for a spherical Earth?

4. How long have we known that the Earth was spherical?

5. Roughly, how was the circumference of the Earth initially determined?

6. What is the celestial sphere concept all about?

MOTION PROBLEMS (classes 3-5)

You will likely be able to do many of these problems, but possibly not all. Fret not, physics phriends! Try them all.

1. Determine the average velocity of your own trip to school: in miles per hour. Use GoogleMaps or something similar to get the distance, and try to recall the time from your last trip. Use your trip from home to Towson, or something that makes sense to you.

2. Consider an echo-y canyon. You stand 200-m from the canyon wall. How long does it take the echo of your scream (“Arghhhh! Curse you Physics!!!”) to return to your ears, if the speed of sound is 340 m/s? (Sound travels at a constant speed.)

3. What is the difference between traveling at an average speed of 65 mph for one hour and a constant speed of 65 mph for one hour? Will you go further in either case?

4. What is the meaning of instantaneous velocity? How can we measure it?

5. How far will a light pulse (say, a cell phone radio wave) travel in 1 second? In one minute? In one year?

6. What is the acceleration of a toy car, moving from rest to 6 m/s in 4 seconds?

7. What does a negative acceleration indicate?

8. Consider an automobile starting from rest. It attains a speed of 30 m/s in 8 seconds. What is the car’s acceleration during this period, and how far has it traveled?

QUESTIONS SPECIFICALLY RELATED TO THE ACCELERATION DUE TO GRAVITY (class 5):

9. What is the acceleration due to gravity? What does this value mean?

10. How does the acceleration due to gravity vary on the Moon? On Jupiter?

11. If you are “pulling 5 g’s”, what acceleration do you experience?

12. If you drop a pebble from a bridge into a river below, and it takes 2.5 seconds to hit water, how high is the bridge?

13. Drop a bowling ball from atop a high platform. How fast will it be traveling after 3 seconds of freefall?

14. How long will it take a rock falling from rest to drop from a 100-m cliff?

15. You throw a baseball straight up into the air with an initial velocity of 22 m/s. How long will it take to reach apogee? (Hint - consider the acceleration to be -9.8 m/s/s.)