3-13

Friday, March 13th, 2009.

Today we began class with 2 Daily Questions. The questions involved centripetal force. Ex. Anna Lititcal is practicing a centripetal force demo at home. She fills a bucket with water, ties it to a strong rope, and spins it in a circle. Anna spins the bucket when it's half full and when its 1/4 full. Which case requires more force to spin the bucket in a circle. Answer: the one that's half full. You use the equation Fc=m x v(squared)/r

We had no homework last night so we didn't have to go over that.

After going over the DQ's, we reviewed the lab on page 5. We looked on the last page of the packet and just filled in the blanks.

Ex. problem from the lab. You are going around the 30 m radius corner at 15 mi/hr. Your car is 1000 kg and will need about 1500 N to make the turn. 1500 N x 16 = 24000 N

After going over the lab, we took out page 2 and made predictions for question 2. Then we tested it and discovered that the acceleration moves inward...the same as the force!! Woah. This is because F=ma and Newton's 4th law tells us that force and acceleration ALWAYS have to be the same direction. picture

We started working on Ac and Fc on page 9 and 11. It's kinda tricky. But..it was allllll worth it because Mr. Manning got so excited talking about it. Then we just worked ona few practice problems on pages 11-13. Sadly, we have homework over the weekend. We have to finish pages 11-13 due Monday.