Unit 1- Long Answer Questions Facts Flashcards
Special theory of relativity
F = ma cannot be used for a particle traveling at very high speeds because its mass increases
Factors that affect drag force
- surface area
- density of fluid or viscosity of fluid
- speed or velocity
- (NOT weight or mass)
Factors that affect thinking distance
- speed
* anything that affects reaction time e.g. Alcohol/ drugs, tiredness, distractions
Factors that affect braking distance
- speed
- anything that affects friction e.g. Wet road, worn brakes, worn tyres
- mass of car
GPS
- uses several satellites
- which send out signals using microwaves
- the GPS receiver detects the signals and work out the delay time
- the distance to each satellite is calculated using delay time x speed of light
- trilateration is used to locate the car
Airbags
Airbags are triggered by a very large deceleration triggering a chemical reaction to produce a large volume of gas in a very short time
Airbags, seat belts, crumple zones- stopping distance explanation
- the distance moved while stopping increases
- but the work done to stop the car is the same
- therefore the forces is less because W=Fd so F = W/d
Airbags, seat belts, crumple zones- stopping time explanation
- the time taken to stop increases
- but the change in velocity is the same
- therefore the acceleration is less because a= (v-u)/t
- therefor the force is less because F=ma
Experiment to determine the acceleration of free fall
- measure height of drop using a ruler or tape measure
- measure time of drop using stopwatch
- use g=2s/t^2 to find the acceleration
Experiment to determine the centre of gravity of an object
- suspend the object from a point
- mark a vertical line on the object using a plumb line to find the vertical
- suspend from a second point and mark another vertical line
- the point where the lines cross is the centre of gravity
Experiment to determine the Young modulus of a metal in the form of a wire
- measure the original length using a ruler or tape measure
- measure the extension using a traveling microscope with a marker
- measure the force using a newtonmeter
- measure the diameter of wire using a micrometer
- calculate area
- calculate the YM using the formulas or stress, strain and YM
Galileo & Aristotle
- Aristotle said that heavy objects fall more quickly than light objects
- Galileo: all objects fall with the same constant acceleration
- They hit the ground at the same time
- Proving that objects of different mass fall with the same constant acceleration