3/11 Physics update and homework due 3/18

Hi folks,

Today we spent quite a bit more time reviewing some energy math problems. This is fairly tough and the quizzes seemed to indicate it could use a bit more work. We also got a bit deeper into waves and actually used the formula Velocity = Wavelength x Frequency to determine the velocity of a Slinky wave.

Homework for this week is to:

Do the Think and Explain Questions on page 388 of the Conceptual Physic book #'s 1-5

Do the think and solve problems on page 399 #'s 1 - 4

Also, work through the bowling ball problem that you did for the quiz today at home. It certainly looks like many of you may want to spend a bit more time on this. Please hand these questions in next week as well. The answers are at the bottom so that you can be sure you get them right. This question will keep reappearing in different forms on the quizzes and so it is in your best interest to get this material down pat.

EXTRA CREDIT: Find a swing and figure out the frequency and period of the swing.

EXTRA CREDIT: Go to a pond or a pool and find the frequency, wavelength and velocity of some water waves you create.

A bowling ball is rested on top of one of those ramps at the 19m (62 ft) bowling lane. If the ball has a mass of 7lbs (3kg) and the top of the ramp is 1m off the ground…

a. what speed will the ball have at the bottom of the ramp?


b. if the ball is going at 3m/s by the time it hits the pins, what's the friction force of the alley?


c. what energy did the ball lose going down the alley?



d. whats the energy efficiency of the ball/alley combo?


e. if the ball comes to a rest after hitting 1 pin, what energy did that pin get?







A bowling ball is rested on top of one of those ramps at the 19m (62 ft) bowling lane. If the ball has a mass of 7lbs (3kg) and the top of the ramp is 1m off the ground…

a. what speed will the ball have at the bottom of the ramp?

4.5

b. if the ball is going at 3m/s by the time it hits the pins, what's the friction force of the alley?

.9N
c. what energy did the ball lose going down the alley?
16.5J


d. whats the energy efficiency of the ball/alley combo?
45%

e. if the ball comes to a rest after hitting 1 pin, what energy did that pin get?

13.5