Homework - 9/28/10

A baseball is launched horizontally from a hillside as shown above. The baseball is thrown with an initial speed of 12 m/s and lands 41.6 meters down the hill, L.
a. Determine how long the ball is in flight between points P1 and P2.
b. Determine the speed of the ball just before it strikes point P2.

Homework - 9/20/10

A bear is at a local park, drowning his sorrows the way he knows best - by drinking a mug of honey. Sad that his bear family has deserted him and that his bloodlust for humans has made him a fugitive, he slides the mug down the table in frustration. The mug slides off the table horizontally and strikes the ground 1.40 meters from the base of the table. If the tabletop is 0.86 meters high, what velocity did the mug have when it left the table? What is the mug's speed and direction just before it hits the ground.

Homework - 9/15/10

The position function below represents a rock thrown off a cliff.

a. What is the rock's displacement after the first 10 seconds of its flight?
b. What is the rock's velocity as a function of time?
c. What is the rock's velocity after the first 10 seconds? (Write the vector form, then find the magnitude and direction.)
d. What is the rock's acceleration as a function of time?
e. What is the rock's acceleration after the first 10 seconds?
f. Does your answer to part e make sense? Explain.

Free Response Review - Chapter 1

The motion graph represents a car on a straight-line track.
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(a) Describe what happened to the car at t = 1s.
(b) When is the car accelerating the most? Explain how you know.
(c) What is the car's acceleration during that interval?
(d) How far did the car travel between t = 5s to t = 7s?
(e) Plot the car's acceleration versus time.

Memorizing Equations

A touchy subject. Here's the thing, it's really easy to make an argument for not memorizing equations - that's why we didn't memorize them last year, but there's a lot more at stake now and, to put things in perspective, we're in a college course now.
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The best argument for why we should memorize equations is because you won't be given an equation sheet for the multiple choice section. And you don't want to be forced to skip multiple choice questions because you don't have an equation memorized. There aren't a ton of M.C. questions that involve using an equation, but there's enough of them to put you at a severe disadvantage if you don't know the equations. I understand it's a lot to ask, especially considering the amount of equations we deal with and memorizing them definitely takes a lot of time. I can offer a few tips to help with the process:
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1. Practice solving homework problems without looking up the equation and then checking later to make sure you've picked the right one.
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2. Keep a copy of the equation sheet somewhere visible, where you'll see it often. (I keep mine on all of the mirrors in my car. The sheer panic that's induced when switching lanes has burned those equations into my mind forever.)
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3. Try a mnemonic device or a unique way to remember the equation. (For example, I memorized the quadratic formula to the tune of pop-goes-the-weasel.)
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4. Practice them using flash cards.

Chapter 1 Review

Remember: If you can't see the image, click on it to view in another window.

1. For each of the motion graphs shown above, describe, in detail, what the motion would look like.

2. For each x-t graph shown above, create the corresponding velocity and acceleration versus time graphs.

3. For each v-t graph shown above, create the corresponding x-t graph.

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4. At a local football game (let's just say Carrick), a running back flattens a linebacker and continues running at a constant velocity of 10.5 m/s. The instant the linebacker hits the ground, he gets back up and starts running from rest to tackle the running back. If the linebacker accelerates at 1.9 m/s^2, how much time will it take to catch the runner? How far will they have traveled from their original position?

Homework - 9/2/10

A wealthy businessman has been reduced to taking the bus to work. The bus driver, assuming that a businessman certainly wouldn't be waiting for a bus, passes up the bus stop, continuing with a constant velocity of 20 m/s. The businessman starts running from rest, but can only accelerate at 1.5 m/s2. How much time will it take the man to catch the bus? Also, how far did he have to run?


At the end of this problem, explain whether this is a reasonable answer or not and explain how you know. You could also explain if it would even be possible for a human to cover that distance in that time.