Newtons laws of motion Flashcards
What is newton’s second law
the accelertaion of an object is proportional to the resultant force acting on an object and inversely proportional to the mass of each object .
experessed as
resultant corce = mass a
f=ma
what is newtons first law
an object will stay stationary or continue moving at the same speed and direction unless a resultant force is applied .
how do u work out inrtia
force/acceleration
tendency for an object to stay at rest or in uniform motion
how to calculate wieght
weight =mg
what is a force
a force is a push or pull that acts on an object because of its interactio ith another object.
what can forces do
forces can hage the shape
motion
or state of rest
describe motion of diver enetring water
as diver enters wate , they diver will decelerate as air resistance in water is greater than in the air , Upwardds force on diver m so upwards resultant force .
what is newtons third law
when two object interact with eachother they exert equal and opposite forces on eachother .
example of contact force
gravity
example of noncontact
air resistance
menng of proportional
bigger force means more accelerationin
inversely proprotional
bigger mss ,less accelration
what is reusltant foce at constant vvelocity
zero - as all oher forces acting on object are zero
what does braing force depend on
spead of the vehicle as breaks are applied
mass of the vehicle
equation trinagle for thinking ditance
thinking distance
speed *reaction time
what is braking distance
the distance travelled by the vehicle after dirver applies break
How do u calcule braking distance
f=m*a =brking distance
how do u calculate stopping distance
stopping ditsnce = thinking distance +brakinng distance
what factor affect thinking ditsance and why
tiredness and alchol affect thinking ditance as they increase thinking distance so stopping distance is greater .
And mobile
factors affecitng braking distance
weaher -slippery-stopping distance increases
Worn out tyres - take longer to break
Required practical 1
accelration is proportional to FORCE
why would more mass =more inenerita
as it is more difficult to stop start and change direction
independenr variabalesof p1
independent-change in mass
Dependent variable -accelration of troley
control - 20cm intervals on bench
Method for p1
Attach a string to the object and hang the string over a pulley on the edge of the
table.
2. Connect a weight stack to the other end of the string.
3. Use either a ruler and a stopwatch or a set of light gates to measure the velocity
of the object as it moves.
4. Add a weight to the weight stack and record the velocity of the object at different
points.
5. Vary the weights on the weight stack and record the change in velocity for each weight
improvement for both practicls
use a light gate - more accurae timngns
extend practical
further distances , more masses
requried practical 2
acceleration is inversley proportion to mass
required practical variables
independent varibales - changin mass in trolley
dependent - acceration
contol - 20cm intervals on bench
method
record intial mass of trolley
attach chosen mass to a string which owuld be a constant force on the teolley
release trolley andsimultaneously start stopwatch and time how long it takes for the trolley to ravel
repeat the pervious steps by increasin mass of trolley eachtime .
how to work otu acceleration
change in velocity /time taken
newtons first law
if the resultant force acting on a stationary object is zero , then the object will remain stationary , or keeps movig at the same spped in the same direction .
Describe sky diver ju,pingout
as soon as they jump , the sky diver accelerates rapidly , as th only force acting on them is weight , this is due to gravity .
Downwards resultant force .
They skdiver experiences friction with the air molecules this is air -reistnce .
However weight is greatee rhna air restiance so continues to accelerate downwards .
as the velocity increases - air resistance also increases
at a certai n point both forces are balaned , has reached terminal velocity - reusltant force is zero .
Open Parachute :- surface increasses , air resistnce mssively increases .
At this point , air resistance now greater than the weight so resultant force is upwards .
This causes the skydiver to decellerate , velocity decreses =air ressitane increses .
Describe sky diver ju,pingout
as soon as they jump , the sky diver accelerates rapidly , as th only force acting on them is weight , this is due to gravity .
Downwards resultant force .
They skdiver experiences friction with the air molecules this is air -reistnce .
However weight is greatee rhna air restiance so continues to accelerate downwards .
as the velocity increases - air resistance also increases
at a certai n point both forces are balaned , has reached terminal velocity - reusltant force is zero .
Open Parachute :- surface increasses , air resistnce mssively increases .
At this point , air resistance now greater than the weight so resultant force is upwards .
This causes the skydiver to decellerate , velocity decreses =air ressitane increses .
So sky diver falling at lower temrinal velocity , safe for them to hit the ground
factors affecitng terminal velocity
mass - bigger mass-larger termial velocity
larger tsurfae area - lowee the terminal velocity
Density of fluid - denser the fluid - lower the terminal velocity .
terminal velocity meaning
velocity reached by an objects when the drag force on it is euqal and opposite to the force making it move .
