Forces and motions Flashcards
what is the equation for speed
speed= distance /time
what is the equation for acceleration
acceleration= Change in velocity/ time
How do you carry out the investigation of motion
- set a ramp up
- You will need two/three light gates one at the start one at the end
- mark a line on the starting point ( to make sure you start the toy car from the same point each time)
- measure the distance between each light gate or marking ( this will be used to work out the average speed)
- let go off the car before the the light gate so it rolls down the slope
- the light gate should be connected to a computer, when the car passes the light gate the light beam will be broken and a time is recorded (data logging)
- Repeat 3 times and calculate an average
- use formula speed= distance/ time
how do you work out the acceleration on a velocity time graph
find out the gradient
How do you work out distance travelled on a velocity time graph
by working out the area under the graph
what is a vector quantity
Has direction and magnitude
what is a scalar quantity
only has magnitude
what are examples of scalar quantities
examples
- Speed
-distance
-mass
-temperature
what are examples of vector quantities
- velocity
-displacement
-acceleration
-lift
-drag
-force
what is the equation for resultant force
resultant force= mass x acceleration
how do u work out resultant force across a line
Add forces in the same direction
minus forces in opposite directions
what is friction
a force which opposes motion
what is the equation for force
force= mass x acceleration
what is the equation for weight
weight= mass x gravitational field strength
how do you work out stopping distnace
stopping distance= thinking distance + breaking distance
what factors effect thinking distance
How fast you are going
reaction time
what factors effect reaction time
-alcohol
-drugs
-age
-inexperience
-tiredness
what factors effect breaking distance
- How fast you are going
- grip
-Friction
- road surface
-weather conditions
-tyres - mass
- conditions of brakes
what does hooks law say
extension is proportional to force
- an object will obey hooks law if a pair of opposite forces are applied to each end
when does hooks law stop working (Hint refer to graph)
- there is a limit to the force you can apply for Hooke’s law to stay true
- when the force becomes great enough the graph start to curve
-then it reaches an elastic limit
- if a force is applied after the elastic limit, the material will be permanently stretched
- some materials like rubber only obey hookes law for really small extensions
what does the E on the hooks law graph represent
Elastic limit
