Unit 1:Our Dynamic Universe Flashcards
What is a balanced force?
Forces are balanced, no forces acting on the object.
What is acceleration?
Rate of change of velocity.
What is a scalar quantity
Only magnitude.
What is a vector quantity?
Both magnitude and a direction.
What is an elastic collision?
Kinetic energy is conserved and momentum.
What is an explosion?
Two objects move apart during an explosion, the kinetic energy gained comes from stored energy in a spring or chemical.
What is impulse?
Average force x time. The cause of change in momentum.
What is an inelastic collision?
Kinetic energy is lost, momentum is conserved.
What is the conservation of momentum?
Same value before and after a collision if no other forces are acting.
State Newton’s 1st law.
Object will remain at rest or continue to travel at constant speed in a straight line-unless acted upon by an unbalanced force.
State Newton’s 2nd law.
Unbalanced force acts on an object causing it to accelerate.
State Newton’s 3rd law.
For every force there is an equal but opposite force.
What is tension?
Pulling force applied by a string or cable on another object.
What is friction?
Force that opposes the motion of all objects.
What is a projectile?
An object that has both a horizontal and vertical component to its motion.
What is a satellite?
An object in orbit around another.
What is the frame of reference?
Background against which measurements are made.
What is invariance?
Same for all observers in all observers in all frames of reference.
What is a muon?
A sub-atomic particle with a short life.
What are the postulates?
When two observers are moving at constant speeds relative to one another, they will observe the same laws of physics.
Speed of light in a vacuum is the same for all observers.
What is Hubble’s law?
The further away from the Earth an object is, the faster it is moving away from the Earth. Only applies to very distant objects.
What is Hubble’s constant?
Recessional velocity of an object divided by the distance from the Earth.
What is recessional velocity?
Velocity at which a distant object is moving away from the Earth.
What is red shift?
Spectra of all distant objects are shifted towards the red end of the spectrum, the faster an object is travelling away from the observer, the more it’s spectrum is red shifted.
