January 2014 Flashcards
What is the difference between vectors and scalars?
Both have magnitude but vectors have direction also.
Examples of scalars?
Density, energy, speed.
Examples of vectors?
Force, momentum, velocity.
Example of Brownian motion?
Smoke particles in air.
What shows Brownian motion?
Smaller particles are hitting larger particles, which you can see.
Particles in ice?
Regular pattern, fixed position, little space between particles.
Particles in water?
Irregular pattern, able to move past each other, little space between particles.
Particles in steam?
No pattern, able to move freely, larger space between particles.
How does an air bag reduce injury?
Momentum reduced, by same amount, over a longer time, so force reduced, less force means less damage.
What happens to a ray when it enters plastic?
Slows down.
How do you know a metal is soft?
Material is capable of being magnetised but does not retain its magnetism.
What happens when a d.c is replaced with an a.c?
Field switches polarity, field weaker.
