1. October 3, 2005 Homework Homework:  Review ALL labs and notes nightly. FINAL EXAM IN four PERIODS. You will need a calculator today.

2. Newton’s 3 rd Law When one body exerts a force upon a second body, the second body exerts an equal and opposite force upon the first body. Pushing a Car:Action-Shove a car forward Re-action-the car pushes back on you with equal force Rowing a Boat:Action-Push the water back with paddle Re-action-the water pushed forward on the paddle making the boat propel forward Shooting a Gun:Action-exploding gun powder pushes bullet forward Re-action-the bullet pushes the gun backwards

3. Momentum Newton called this “quantity of motion.” Momentum = mass x velocity p = mv If either mass or velocity increases, momentum is increased. Momentum units come directly from the mass and the velocity and are written right next to each other. Example: kg · m/secg ·mm/sec

4. 1. What is the momentum of a bird with a mass of.018 kg flying at 15 m/sec north? p = mv p =.018 kg x 15 m/sec p =.27 kg·m/sec 2. A 50 kg child is walking with a velocity of 100 m/min. What is the momentum of the child? p = mv p = 50 kg x 100 m/min p = 50000 kg·m/min 3. A golf ball travels at 16 m/sec, while a baseball moves at 7 m/sec. The mass of the golf ball is.045 kg and the mass of the baseball is.14 kg. Which has greater momentum? p = mv p =.045 kg x 16 m/sec p =.72 kg·m/sec (golf ball) p = mv p =.14 kg x 7 m/sec p =.98 kg·m/sec (baseball) The baseball has more momentum.

5. 4. The momentum of a boat is 100,000 kg ·m/sec with a velocity of 5 m/sec. What is the mass of the boat? p = mv 100,000 kg·m/sec = m x 5 m/sec 5 m/sec m = 20,000 kg Use the remainder of class to complete labs 25 & 26. These are the last two in this series! HOMEWORK: Review completed labs, work on practice problems assigned on Friday, study all vocabulary, and memorize all formulas.

6. Lab Goals Today  You must complete labs 25 and 26.  If you have extra time at the end of the period:  Look back over labs 17 – 26. (We did not do # 19.)  Do you have the objectives?  Do you have the variables?  Do you have the QUESTIONS COPIED?  Have you answered EACH QUESTION fully? Did you EXPLAIN your thinking?  Do your answers support the objectives? I  What grade would I give you for each lab? 3. Study for the test! Write your own questions. Quiz your neighbor on vocabulary and formulas. Do you know the formula for speed/velocity? Acceleration? Momentum?