Worked out solutions to practice problems

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HW related to pendulum lab

1.  Graph period of ONE swing (T, in seconds) vs. length (L, in meters).  T will be on y-axis and L will be on x-axis.  Make certain that length is converted to meters (if you used cm). 2.  Print out graph. 3.  Make a third column of data - square root of each length measurement (in meters). 4.  Think/write about this:  What makes a simple pendulum "simple"?  What is assumed to be true about the simple pendulum? 5.  If you have the video from the giant swing, try to determine the period of one oscillation (one complete swing of the person).  We are going to try to compare theoretical pendulums to the giant swing in our next class.
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Momentum practice problems (answers included)

Review the notes on the blog (2 posts ago) and try these questions and problems (similar to what we did in class today, Monday 4/2). 1.  Give an example of 2 different conservation laws. 2.  What is the mathematical definition of momentum? 3.  What is the conservation of momentum, and when do we think about it (under what specific circumstances)? 4.  A 300-g cart moving at 40 cm/s hits another 300-g at rest.  Friction is very low.  What do you expect will happen exactly?  Give numbers if possible. 5.  A 60-kg figure skater skating at 8 m/s collides directly with a 40-kg skater initially at rest.  Friction is very low and the two become intertwined on the ice.  Calculate the speed of the two of them together after the collision.  (Hint:  First find the momentum of the 60-kg skater, and then use conservation of momentum to solve for the final speed of the two together.  This is like the velcro cart collisions.) 6...
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For Wednesday's class

This homework is related to the discussion we had in class about horizontal motion vs. vertical motion. A baseball is thrown horizontally at 30 m/s (which is a pretty typical Park pitcher throwing speed).  It leaves the pitcher's hand 1.5 m above the ground. 1. How long would the ball take to hit the ground, if it does not hit a bat (or anything else) first?  Keep in mind this is just like a dropped object, since there is no horizontal acceleration for the ball (after it leaves the pitcher's hand). 2.  How far will the ball travel horizontally in this time.  Hint:  use v = d/t (since there is no horizontal acceleration). 3.  Is there any time difference between this thrown ball and another ball dropped from the same height (instead of thrown)?  Discuss why. 4.  Challenge question.  If the pitcher were standing on a 0.5 m tall mound,  but otherwise throws as above, how long would the ball take to touch ground and how far would i...
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