Monday Finish School Buses Intro to momentum

Today Seatbelt paper –(Rubric handed out on Tuesday) Pages in yellow workbook to be completed Momentum –In terms of collisions –In terms of games –In terms of people

Yellow Book pages 2 and all parts (might need to go back and complete (only predictions and observations) 27 only the scroll 29(entire page), 30 (only chart) questions 45 (entire page)

Homework Practice Problems p 363 (1,2) Problems on page 366 (1 through 6) 2 nd law problems on pg 367 (1-3)

Would you support a law that requires all school buses to have seat-belts?

Rubric Seat belt paper (50 points) Friday Up to nine points each for: –At least 3 worthwhile reasons for seatbelts –At least 3 worthwhile reasons against belts –Connection between each law to seatbelts Up to six points each for: –Clear statement of position on seatbelts –How well the project written –Condition of project Up to 4 points for: –references from outside articles or other sources

Which would you rather get hit by? 1 bowling ball?1 marble ?

Momentum A quantity of motion Found by multiplying the mass of an object by its velocity Momentum = mass x velocity

Units Momentum = kg m/s Not the same as Forces (N = kg m/s 2 ) Momentum is not a force

Momentum equation P = m v P MV

2nd law and velocity equation can also be drawn in a similar fashion F net = m a D = v t MA t

If the object moves, and has mass, it has momentum

Objects gain and lose momentum due to forces being applied

To catch a tennis ball Your hand must apply force to the ball to make it stop moving

The change on momentum Related to the change in velocity Mass is usually kept constant Related to the amount of force applied Related to the time is takes to achieve the change

To make something stop (Change of momentum constant) Apply a lot of force in a short period of time or Apply a small force over a longer time

The purpose of most safety features in a car is to lengthen the time of the accident Air bags

Seat belts

Padding on dashboard, seats and steering wheel

Crumple zones It takes time for the parts of the car in the crumple zone to be crushed, less force applied to the passenger section

Any other means to protect the passengers during a collision?

Other examples of change in momentum Catching a Foul BallBeing hit by a foul ball

Momentum is conserved Conserved means that the momentum can be transferred from one object to another, but not lost to the system

Newton’s Cradle