P5:forces and motion Flashcards
whats a contact force
when objects physically touch
whats a non contact force
when not touching
whats a vector
a quantity that has magnitude and direction
whats a scalar
quantity that only has magnitude
whats a resultant force
overall force acting on a object
give examples of scalars
distance, speed , mass, energy, temperature
give examples of vectors
displacement, velocity, acceleration, force, momentum
how is thinking distance affected
speed, distraction, alcohol, drugs and tiredness
how is breaking distance affected
speed, condition of breaks, tires and roads, weather condition
what does momentum(kgm/s) =
mass(kg) x velocity(m/s)
what are all the EM emitted by
electrons
how are EM waves produced
when electrons lose energy
What does a higher frequency mean
more energy which means shorter wave lengths
what does work done =
force x distance
what does force = when it comes to elasticity
spring constant (n/m) x extension(m)
what does acceleration =
change in velocity(m/s)/time
what is suvat
s : displacement(m/s)
u : initial velocity
v : final velocity
a : acceleration(m/s^2)
t : time
how do you calculate weight(n)
mass(kg) x gravitational field strength(n/kg)
whats newtons first law of motion
when theres no resultantant force an objects motion is constant
whats newtons 2nd law of motion
force(n) = mass(kg) x acceleration(m/s^2)
what is the practical for acceleration
accelerate trolley with mass on string
use photogates to measure acceleration
change weight on string
draw a force - acceleration graph
straight line across origin which shows that f and a are directly proportional
whats newtons 3rd law of motion
for every action there is an equal an opposite force
in a closed system what happens to momentum before an event and after an event
total momentum before and event is equal to the total momentum after and event
what happens in collisions
Momentum is conserved so the momentum of object increases
Which decreases the momentum of the other object
Mass of object is constant so velocity decreases
Reasons why speed may change
Surface
Tiredness
Force
What happens when a force moves through a fluid
Force drags on it
It acts in the opposite direction of the object
The greater the speed the greater the drag
What happens to an object falling through a fluid
At the start weight is equal to resultant force
Resultant force causes them to fall
Air resistance is an upwards force that acts opposite to weight
Air resistance is low at the start
Resultant force decreases because of air resistance
Air resistance increases as they collide with more particles
Weight is constant so resultant force decreases and they are accelerating more
Air resistance will increase to the same amount as the weight
No resultant force
So no resultant force
Reach terminal velocity
How does surface area affect air resistance
The larger the area which collisions can take place
More air resistance
Resultant force changes direction
Slow down
Resultant force decreases
Until terminal velocity
