Our Dynamic Universe Flashcards
What is acceleration?
Acceleration is the change in velocity per second
What is Gravitational Field Strength?
This is defined as the weight per unit mass
Satellite Orbits
Satellite experiences unbalanced force, must be accelerating due to change in direction, constant horizontal velocity and constant vertical acceleration causes curved path. Curve in satellite is same as earth so stays at the same height above the surface, orbit.
Lift experiment: what does it mean when there is a larger upward force?
There is an upward acceleration
Lift experiment: what does it mean when forces are balanced?
The lift is at rest or has a constant velocity
Lift experiment: what does it mean when there is a larger weight?
There is a downward acceleration
What is conservation of energy?
The principle that total energy is conserved
What is momentum
Momentum is the product of the mass and velocity of an object
What happens to kinetic energy in an elastic collision?
It is conserved
What happens to total momentum in a elastic collision?
It is conserved
What happens to kinetic energy in an inelastic collision?
It is lost
What happens to total momentum in an inelastic collision?
It is conserved
What happens to momentum in an explosion?
It is conserved
What happens to kinetic energy in an explosion?
It is greater after
What happens to total energy in an explosion?
It is conserved
What is impulse?
The change in momentum of one mass in a collision or explosion
What are the postulates?
All observers measure the same speed of light and laws of physics are the same in all frames
What is time dilation?
Time dilation is when the time on a moving clock appears to have slowed when measured by a stationary observer
What is length contraction?
Length contraction is when an object appears to be smaller when measured by a stationary observer when it is moving relative to them
Why can the observer ignore relativistic effects with an object with a velocity less than c?
Because (v/c)^2 is approximately equal to zero when v is less than or equal to c
What is the Doppler effect?
The name given to the frequency shift heard by an observer to a sound with relativistic motion between them
What happens to the frequency when a source is moving away from a stationary observer?
It will be lower
What happens to the frequency when a source is moving towards a stationary observer?
It will be higher
What was the Big Bang?
The Big Bang was an inflation of a singularity
What is evidence for the Big Bang?
Red shift of galaxies, cosmic microwave background radiation and the abundance of light elements
What is red shift?
Red shift indicates that the source of light is moving away from the observer
What is Cosmic Microwave Background Radiation?
It proves the Big Bang because when plotted against wavelength it produces a graph that shows the universe is cooling after the Big Bang
Abundance of light elements
After the Big Bang there were only fundamental particles from these small lighter elements are likely to form which is constant with observations
What is dark energy?
This is the name given to the energy source that cosmologists think is causing this expansion
What is dark matter?
It is not normal matter as it produces a gravitational effect but does not interact with normal matter
