2. Momentum An objects momentum is its mass multiplied by its velocity Momentum = mass * velocity Kg m /s kg m/s Mass = 1000 kg V = 6 m / s Momentum = 1000 *6 = 6000 kg m / s

3. Momentum & collisions When two objects collide they exert an equal & opposite force on each other The force (they apply) = change on momentum time

4. Reducing the force in accidents You can explain air bags, seat belts etc using momentum Ie the longer the time an accident takes means momentum is changed over a longer time reducing the force Mass = 1000 kg Initial velocity 5 m/ s If it stops in 2 seconds Force = 1000 * 5 2 = 2500 N Force = 1000 * 5 5 = 1000 N If it stops in 5 seconds

5. Momentum can explain…… Rockets Momentum of gas this way = Momentum of rocket this way Recoil of a gun Mass * velocity of cannon = Mass * velocity of cannon ball The momentum is conserved, so the momentum to the left must equal momentum to the right

6. Momentum & collisions Carriage A is rolling towards carriage B which is stationary. They stick together after the crash. What is the new velocity? A Mass 10 000 kg. Velocity 5 m/s B Mass 10 000 kg. Velocity 0 m/s A + B Momentum before the crash = momentum after the crash m * v + m * v = m * v 10 000 * 5 + 10 000 * 0 = 20 000 * V 50 000 + 0 = 20 000 * V 50 000 = V = 2.5 m/s 20000

7. Polarization of light (Sunglasses)

9. Light normally travels in random planes Filters can “polarize” light, only light in a certain plane can get through Polarized sunglasses block out horizontal light (for example light that reflects off light surfaces such as the sea. Only light in the “Y plane” gets through. Reducing the strain on your eyes.

10. Adding waves If they are in phase (crests line up) = Constructive interference If they are out of phase (crests and troughs line up) = Destructive interference

11. Two slit experiment Laser light source