Dynamic Universe UNIT 1 Flashcards
Is momentum a vector or scalar
Vector
3 types of momentum
Collide and split
Collide and lock
Explosion
Total momentum before =
Total momentum after in the absent of External forces
Formulas for momentum
M1U1 + M2U2 = M1V1 + M2V2
M1U1 + M2U2 = (M1+M2) V
M1U1 +m2 (-u2) =m1 (-v1)+m2v2
If kinetic energy is not conserved then its
Inelastic
Is energy is conserved then its
Elastic
Equation of instantaneous speed
Length of card ÷ time through gate
Negative acceleration is
Deceleration
On a velocity time graph the acceleration is
The gradient of the graph
On a velocity time graph the distance is
The area under the graph
Definition of vector
Both magnitude and direction
What’s a scalar
By magnitude
The gradient of displacement time graph
Is velocity
Area under acceleration time graph provides
Velocity
Ares underneath velocity time graoh provides
Displacement
Area under acceleration time graph provides
Velocity
When figuring out what equation to use for the equation of motion questions
SUVAT
We can only use Suvat when the acceleration is
Uniform (constant)
What is a friction compensated slope
It means that the slope is at a perfect angle that the forward force is equal to the frictional force
What is acceleration due to gravity
-9.8m/s
3 types of uncertainties
Systematic
Random
Reading
What is a systemic error
When all the measurements are off by the same amount
How to calculate a reading uncertainty
Using the half the smallest division of the measurements ypu are using.
Then turn it into a percentage
Newtons frist law
An object remains at rest or a constant velocity unless acted upon by an unbalanced force
Newtons second law
An object will accelerate in the direction the unbalanced force is applied q
Newtons 3rd law
Every action has an eaqul and opposite reaction
1 Newton
The force that will accelerate a mass 1kg at 1ms-1
What is friction
A force that opposes motion
Explain terminal velocity
Initially the object in free-fall would be accelerating due to gravity. And the weight is much greater than the air resistance. So the forces are unbalanced.
As the velocity is increasing that air resistance also increases making the acceleration decrease.
Eventually the object reaches maximum velocity and the forces become equal.
What is terminal velocity
When an object is in free fall and reaches maximum velocity
What is the acceleration at terminal velocity
0
Two ways to workout the unbalanced force
F=ma
Force unbalanced = thrust-weight
Resolving forces vertically
R-W = ma
Formula for tension
Unbalanced force = tension - friction
When tension is greater then frictional forces
It will accelerate and increase in velocity
When two objects are in contact both pull and pushes they always have the same
Acceleration
Forces on a lift accelerating up
The tension force must be greater then the weight as it is moving upwards against gravity
Forces on a lift accelerating down
The tension is smaller then the weight because the lfit is moving down with gravity
Forces on a lift decelerating down wards
Weight is greater then tension
Forces in a lift delecelerting downwards
Tension is greater then weight
What happens to the horizontal force and vertical when the angle is increased
The horizontal forces will be smaller
The vertical force will be greater
Travelling down the slope
Mgsin0
When forces acting down a slope if friction is less than mgsin0 the sledge will
Accelerate
When forces acting down a slope If friction is balanced then
The sledge will move at a constant speed
Forces acting down a slope if friction is greater then
The sledge is deaccelerating
Force acting down on a slope
Mgsin0
Force perpendicular to the slope
Mgcos0
What is a projectile
Any object that has been thrown and is under the influence of a gravitational field
What are the forces acting on a projectile
It’s weight acting vertically downwards
Horizontal projectiles
Constant velocity
No forces
V=d/t
Vertical projectiles
Constant downwards accerlatration
SUVAT ONLY
What are horizontal and vertical motions linked byv
Time
Is travelling up positive or negative
Positive
Is travelling down positive or negative
Negative
For projectiles at an angle horizontal velocity can be found using
Vh=Vcos 0
For projectiles at an angle how to you work out the vertical velocity
Vv=Vsin0
What is work done
It is the engery transferred when sn object moves a distance
What is power
Energy transferred per second
For a collide and split what equation is used
M1u1 +m2u2 = m1v1 +m2v2
What equation is used for collide and lock
M1u1 + m2u2 =(m1 +m2)v
What is the units of impulse
Ns
Impulse =
Change in momentum
What happens on a force time graph when a softer material is used
The time of impact is longer since the object can mould to the object, this means the force will be less over a longer time
Is engery conserved in an explosion
Nob
Is the knetic engery conserved in a collide and lock
No
Is engery conserved in collide and split
Yes
What shows a systematic uncertainty
The line if best fit doesn’t go through the orgin
Definition of an elastic
If the knetic engery before is the same as the knetic engery after
Definition of inelastic
Engery is greater before then afterv
What’s the vertical velocity when it reaches its maximum height
Zero ms-1
What’d a gravitational force feild
When an object will feel a force due to gravity in a region in space
What’s displacement
The shortest distance between the starting point and finishing point of a
journey,
Speed
The distance travelled per unit time.
velocity
displacement per unit time
acceleration
The change in velocity per unit time
deacceleration
negative acceleration which indicates that an object is slowing down.
friction
opposes the motion of an object
what is drag
a force which oppose the motion of an object
Tension
The pulling force on a bar, string, rope, cable or chain.
Mass
quantity of particles that make up an object
weight
force due to gravity acting and object
work done
force applied to move an object a certain
distance.
whatis impulse
Impulse is equal to the change of momentum
what is the doppler effect
the apparent change in frequency as the source moves relative to an obsever
curing the doppler effect when the sound is travelling towards them the sound is?
negative
during the doppler effect when the sound is travelling
away from them the sound is?
positive
When a source is moving away from you
The wavelength is increased for thr light is red shifted
When the source is moving towards ypu then
The wavelength is decreased making it blue shift
When working out the time in a projectile you uses
The initial vertical velocity
Special relativity can only happen is the velocity is
Constant
What r the two postulates for special relativity
The laws of physics are the same in any frame of reference.
The speed if light is constant.
What Is t’
The time observed by the stationary observer
What is t
It is poper time and is the time experienced by the moving objects
The closer you get to the speed of light the greater the
Time dilation
When an object is moving close to the speed of light what happens to the object
The object contracts
In what direction do you contract when trialing at the speed of light
In the direction of motion
L’
The length measured from observer
L
Porper length moving
What is dark matter
Rotation of stars within the galaxy are rotating faster than expected by the mass calculated, this must be due to an undetected mass repsent
Dark engery
The universe is expanding more quickly than expected. Objects moving away are accuratrating due to an unbalanced Frocester acting against energy
The further the object
The greater the receding velocity
Hubles law allows us to calculate what
Rhe age of the universe
2 peices of evidence that support the big bang theory
Cosmic microwave background radiation
And hubbles law
Explain why lines on 2 different spectrums are different for the same emisson
Is has been red or blue shifted
Two facts about black
Best absorber of heat
And best radiator of heat
What effects the radiation embitted by blackbody
Temperature
Basic rules for blackbody radiation
The greater the temperature the shorter the peak wavelength
The greater the temperature the greater the power
Why did stars emitte different colours
Difference in surface temperature of the stars
What is a blackbody emitter
Is a source that only emits radiation due to its own properties
It does not reflect radiation from its surroundings
What’s an example of a blackbody
Stars
Why do larger stars glow more brightly ?
The power radiated by an object also depends on it’d surface area. The greater the surface area thr greater the radiated power. So larger stars glow more brightly as they have a larger surface area
What is the luminosity
The power if the star
Thr total energy given out per second by a star
Is a star is blue
The star has a higher temperature and is a younger star.
What is a starc
Is the fusing of hydrogen atoms to produce helim
High mass star
Will go on it make a black hole or a neutron star
If a star has a low mass it will become a
White dwarf
Explain the life time of a star
It starts with nuclear fusion. Once the star starts to run out of hydrogen at its core it begins to burn the helium. And form heavier elements. The star begins to cool but also grow in size. Then is splits off depending on their mass
What is olbers paradox
If the universe was infinite then you should be able to look anywhere and see a star but since there is gaps in the sky. An expanding universe explains that stars are red shifted so their light will no longer to visible
What is the after glow big bag
Cosmic microwave background radiation
Impulse unitsb
Ns
Explain why the dark lines on the spectrum of sunlight produced
Photons of particular frequencies are absorbed in the sun atmosphere
What happens to the velocity and energy when you increase the angle
The velocity will be less so the engery will be less
When explaining the doppler effect
Talk about how close or far apart the wavefront are
True or false does stellar object admit over s wide range of frequencies
True
Hotter objects emits more
Radiation per unit square area then colder objects
Descrube the method for the rod experiment using a Stopwatch
Measure the total time over a number of swings divide total time by the number of swings
