Review Questions - - Prepare for the final!

(1) Elaine throws a ball straight up and it rises to a height of 10 feet before coming back down. Louise throws a ball straight up at twice the speed at which Elaine threw her ball. How high does this one rise?

(2) Lois puts her solar cells under an electric light in her house, and thus charges up some batteries. Discuss the economics of this - is she getting something for nothing? Could she do better?

(3) True or False: You can save money by listening to the radio in your car, instead of to a similar radio you must plug in in your house.

(4) True or False: If you need to lift a heavy object, you can use a lever to reduce the amount of work you must do.

(5) The lowest note on my cheap, student flute is a middle C.   On a professional flute, the lowest note is a slightly lower one, a B-flat. How does the length of a professional flute compare with mine?

(6) Joe weighs 200 pounds and Phil weighs 150 pounds. Both are equally fit. They hike up Mount Cutler together. Does Joe burn more calories than Phil? Why or why not?

(7) Your car has a braking distance of 50 feet at 30 miles/hour. On a nice day, what is your car's braking distance at 60 miles/hour? at 90?

(8) True or False: If you hit a chime harder, the resulting sound has a higher pitch.

(9) Suppose a teeter-totter has the fulcrum at the middle. A 100-pound kid sits at one end, and a 60-pound kid sits at the other end. Are they balanced? Of course not! However, they find that they are perfectly balanced when their friend sits halfway between the 60-pound kid and the fulcrum. How much does this friend weigh?

(10) If I plug a pair of headphones into my boombox, no sound comes out of the speakers. Can I save on batteries by listening through headphones instead of speakers?

(11) Lydia stands on top of Olin Hall. She throws one superball straight down at 10 feet/second. She throws an identical superball straight up at 15 feet/second. Which ball bounces higher, or don't you have enough information to answer this question? (They bounce on the same type of surface.)

(12) If a ball is thrown up from the ground at 10 meters/second, it rises to a height of about 5 meters. What if a ball with twice as much mass is thrown up at 10 meters/second?

(13) Harold is listening to his radio. Maria tells him that just by touching the radio, she can tell it isn't 100% efficient. How can she be so sure?

(14) The harp strings nearest the harpist are much shorter than those farther away. Which strings does she pluck to get the highest notes?

(15) Whatever your answer to the previous question, how is it that on a guitar all the strings are the same length?

(16) On a rainy day the coefficient of friction between a particular road and a car's tires is 0.4. The driver notes that she can go around one curve at a maximum speed of 30 miles per hour. What quantitative thing about the road does this tell us?

(17) If a car on a loop-de-loop just barely makes it around the top of the loop, when it's traveling upside down, what is its acceleration at the top of the ? at the bottom of the loop? What normal force is exerted on it by the track when it's at the top of the loop? at the bottom?

(18) A kid who weighs 60 pounds stands on a trampoline and is bobbing up and down once a second. She gets off and her older brother, who weighs 140 pounds, gets on. At what rate does he bob up and down? (Neither kid's feet leave the trampoline.)

(19) It's easy to snap a piece of dry spaghetti in half, and pretty easy to snap one of those pieces in half. Keep going with this, though, and it gets really hard to snap a small piece in half. Let's face it, the spaghetti is equally hard all along the original length, so why is it so much harder to snap a short piece in half?