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10/15 / 13 Collisions. Science podcast : Changing foliage Quick force review Discuss Collisions Impulse-momentum demonstrations Review Momentum worksheets Homework: Finish your egg drop device, start your written report, meet at the north end of the football stadium. Learning Objectives.
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10/15/13Collisions • Science podcast: Changing foliage • Quick force review • Discuss Collisions • Impulse-momentum demonstrations • Review Momentum worksheets • Homework: Finish your egg drop device, start your written report, meet at the north end of the football stadium.
Learning Objectives • Use the definitions of impulse and momentum to solve for an unknown • Analyze a situation to determine how to diminish the force that occurs during a collision
Egg drop reminders • We will meet at the north end of the stadium stands at 10 am Thursday. • The length + width + height of your egg drop devise MUST be less than 30 cm total. If it is greater, you may still test it but it will not be eligible for the 6 success points or the extra credit “class favorite” points. • You’ll have 5 minutes to put your large egg in its container. • The report is due Monday 10/21. One 3-4 page report per group. See rubric for details.
Crate was moving to the right Then, the guy pushed the crate 1. If the total force acts in the same direction as the crate is sliding, the crate • slows down • speeds up • remains at same speed • slows down, changes direction and then speeds up going the other way • remains at same speed, but changes direction
Cabinet was moving to the left Then, the guy pushed the cabinet 2. If the total force acts in the opposite direction as the cabinet is sliding, the cabinet would • slow down • speed up • remain at same speed • slow down, change direction and then speed up going the other way • remain at same speed, but change direction
Refrigerator was moving to the right Then, the guy pushed the refrigerator 3. If there is zerototal force acting on on the refrigerator, the refrigerator would • slow down • speed up • remain at same speed • slow down, change direction and then speed up going the other way • remain at same speed, but change direction
Momentum • Momentum is a characteristic of moving matter. • Which has more momentum? A fast gymnast? A fast baseball player? A fast football lineman? Why? • Which has more momentum? A fast volleyball player? A medium volleyball player? A slow volleyball player? Why? • We have a sense that momentum depends on mass and velocity. This is true. • Momentum = mass X velocity or • p = mv. Since v is a vector, p is a vector too.
Impulse and momentum change Newton’s 2nd law Definition of acceleration Change in momentum Impulse Go over Momentum, Impulse, Momentum Change
Impulse Momentum demos • Pounding a nail. We will try to pound in a nail into a small block of wood with the wood on the table, stiff foam, and soft foam. Rank the relative ease of pounding in the nail on each surface. Defend your ranking. • Throw an egg at a sheet. Predict: what will happen to the egg. Why? • Water balloon toss. Develop a plan to catch a water balloon tossed from a long distance away. • Apply these demos to the egg drop activity. How will they help you protect the egg? Go over Controlling a Collision