10/9 Physics class and homework due 10/16

Hi folks,

We got a little mathy today as we took a look at how to solve some, slightly more complicated, acceleration problems.  We also took our knowledge of acceleration and applied it to the concept of gravity.  We will be doing more with gravity next week.

Homework for next week is to practice your formulas by doing the following problems.  Answers are below.  Be sure you understand these.  They are the basis of many of the problems that will be coming soon.  

The formulas for these are in your notes.  Use the soccer ball problem we did in class as a guide for #2 and #3.

1. Whoops, you dropped your cell phone. Well…might as well do some physics.

a. If your cell phone dropped of a 10 m (30 ft) tall building how long will it take before it hits the ground?

b. What speed will your cell phone hit the ground at?

c. What average speed will your cell phone have during the fall?

d. What is the acceleration for your cell phone?

e. Create a velocity vs. time graph for your cell phone.  I do want to see data points for this, not just the shape. (Yay more graphs!!!)

f. Create an acceleration vs. time graph for your cell phone. I do want to see data points for this, not just the shape.

g. Create a distance vs. time graph for your cell phone.  I do want to see data points for this, not just the shape.

2.  A little baseball here.

A pitcher is able to throw a pitch at 45m/s (about 100 mph).

The pitch itself takes 0.1 seconds to throw.

Home plate is 18.4 m (60.5 ft) from the pitcher.

a.  What is the acceleration of the pitch?

b.  How long does it take the pitch to get to home plate?

3.  A drag racer accelerates at 39.2 m/s/s (wow that's fast!!!!) for the entire distance of a 308.4m (1000 ft) track.

a. What time does he cover that distance in? 

b. What is his speed when he crosses the finish line?