Quiz Friday - practice problems here

1.  A ball is dropped from rest from atop a 60-m tall tower.  If it undergoes a standard acceleration due to gravity of  9.8 m/s/s, find the following:

a.  how long it takes to hit the ground

b.  the speed it will have right before it hits the ground

2.  A car is traveling at 30 m/s when the driver applies the brakes, bringing the car to a halt in 3 seconds.  Find:

a.  the acceleration during this braking period

b.  how far the car travels during this period

HW for Monday (equations of motion practice)

Use the equations of motion (where helpful) to solve the following problems.

1.  Consider a car, capable of accelerating from rest at 5 m/s/s.  If it accelerates uniformly for 8 seconds, find:

a.  the velocity after 8 seconds
b.  how far the car has gone in this time

Now assume that the driver applies the brakes and the car uniformly comes to a halt in 3 seconds.

c.  What is the acceleration during this braking time?
d.  How far does the car go during this time?

Draw two graphs that represent:

a.  the displacement vs. time for the entire trip
b.  the velocity vs. time for the entire trip


2.  Imagine that a falling body accelerates at 10 m/s/s.  It is released from a high tower:

a.  If it takes 3.5 seconds to hit the ground, how fast is it traveling immediately before hitting the ground?
b.  If it took 3.5 seconds to hit the ground, how tall was the tower from which it was released?

Keep working on your lab report.  Your draft is due Monday, and the final lab is due Wednesday.

Lab hw

Work on the lab report for Tuesday.  Make sure you have the graph (with line and slope) for the ticker tape part, and calculated velocity for the photogate part.  

Follow the lab sheet for the rest.  The draft will be due 2 classes after our next class.

Weekend - yay!

HW for Monday

1.  Review the distinction between vector and scalar quantities.  Make sure you know the difference between them.

2.  Review the difference between distance and displacement, as well as speed and velocity.

3.  So, we calculated average speeds and average velocities in class.  Here is a question to think about.  My average speed on the way to school was 24 miles per hour.  Imagine that instead of driving safely and obeying the law, I drove at a CONSTANT speed of 24 miles per hour for the entire trip from home to school.  Would I arrive at the same time or not?  Discuss.

4.  What do you suppose "instantaneous speed" or instantaneous velocity is?  How could we determine it experimentally for a car or person?

5.  Imagine a car driving straight at a constant speed of 25 m/s for 5 minutes.  Draw an approximate graph that represents the displacement vs. time for the entire trip.

6.  Two ropes are attached to a boulder that is stuck in the mud.  One person pulls on the boulder with a force of 100-N south.  Another person pulls on the boulder with a force of 250-N east.
a.  Draw this as a problem.
b.  Solve for the total force acting on the boulder - magnitude (number) and angle.  You may need SOH-CAH-TOA to find the angle.

Arduino info

Here is a download link for code for several Arduino projects in the Sik guide:

sparkfun.com/sikcode

And the guide is here:

http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Kits/SFE03-0012-SIK.Guide-300dpi-01.pdf