Our Dynamic Universe Flashcards
Definition of acceleration
The rate of change of velocity (ms-2)
Newtons 1st law
When the forces acting on an object are balanced it remains at rest or a constant speed
Newtons 2nd law
When an unbalanced force is applied to an object the acceleration of the object is directly proportional to the unbalanced force and inversely proportional to its mass
Newtons 3rd law
For every action there is an equal and opposite reaction
What happens is the velocity of an object increases?
The frictional force also increases
Terminal velocity
When an object falls at a velocity where the forces on it become balanced
Principle conservation of energy
Energy cannot be created or destroyed
Law of conservation of momentum
Total momentum before a collision is equal to to the total momentum after a collision in the absence of external forces
What is conserved in an elastic collision?
Momentum and kinetic energy are conserved
What is conserved in an inelastic collision?
Momentum is conserved and kinetic energy is not conserved
How do u determine whether a collision is elastic or inelastic
Calculate the total energy before and after the collision
The area under a force-time graph is equal to….
Impulse
Horizontal motion equation
S=vt
Vertical motion equation
V=u + at
2 theory’s of special relativity
- When two observers are moving at constant speeds relative to one another, they will observe the same laws of physics
- The speed of light (in a vacuum) is the same for all observers
Time dilation….
Increase in time of events on an object moving relative to an observer
Length contraction….
Decrease in length of an object moving relative to an observer
When a source moves towards an observer…..
( - )
When a source moves away from an observer….
( + )
Redshifted….
Light from objects moving away from us are shifted to longer wavelengths
Blue shifted….
Light from objects moving towards us are shifter to shorter wavelenghts
What is dark energy?
The unknown force acting against gravitational attraction
4 pieces of Evidence for the Big Bang
- Hubbles law
- Cosmic microwave background radiation
- Olbers paradox
- Proportions of hydrogen, helium and other elements
Black-body radiation curve
A graph of the emitted radiation against wavelength has a characteristic shape
At all wavelengths…
The radiation emitted per unit surface area per unit time for hotter objects is greater than that for coller objects
Percentage uncertainty formula
Uncertainty\ value x 100
Impulse equation
kgms -1
