Dynamics Flashcards
Inelastic
Momentum is conserved, kinetic energy is lost to heat and sound
Elastic
Momentum and kinetic energy are conserved
Principle of linear momentum
For an interaction between two bodies in a straight line momentum is conserved provided there are no external forces acting
Impulse
Product of force and time as-well as the change in momentum
Newton’s first law
An object will remain at rest or moving at a constant speed unless acted on by an unbalanced force
Newton’s second law
A uniform unbalanced force acting on a a mass will produce a uniform acceleration
Momentum
The product of mass and velocity
Total momentum before=
The total momentum after
Tension
The pulling force of a rope chain or wire
Work done
The force applied to move an object a certain distance
Kinetic energy
The energy possessed by a moving object
Principle of the conservation of energy
Energy cannot be create or destroyed only changed from one form to another
Power
The rate at which energy is converted onto other forms
velocity
displacement per unit time
explosions
there is no momentum before so total momentum after must be 0
crumple zones
area of contact that collapses during a collision to decrease time of contact
accelerating up/ decelerating down
weight increases
decelerating up/ accelerating down
weight decreases
why do satellites not fall to earth
the earth curves downwards at the same rate as the satellite so it never lands
what is freefall
when force of gravity is the only force acting when an object
what is newtons law of universal gravitation
the force of attraction between two objects
inverse square law
double the distance and the force decreases by 4
frame of reference
the background against which measurements are made
galilean invarianace
the principle that within a frame of reference the relative motion of objects is the same
time dilation
fast moving clocks run slow s experience less time
length contraction
the decrease in length of an object moving relative to an observer
fast moving objects are shorter in length to the stationary observer
what happens to the wavefronts of a source moving towards the observer
the wave fronts are closer together so a higher frequency is heard
if the source is moving towards the observer
the equation is negative
if the source is moving away from the observer
the equation is positive
redshift
when an object moving away from us have their light shifted to a lower frequency .
can be used to show how fast a galaxy is moving away from us
hubbles law
most galaxies are moving away from us, the further away a galaxy is the faster its moving
evidence for the big bang
comic microwaves background radiation detected everywhere in space, equally distributed in all directions, the after glow of the big band.
an abundance of light elements, hydrogen and helium - the first to form after the big bang.
cosmological redshift, the galaxies re moving away from us and the light is redshifted
why must there be dark matter
the rate of rotation of the galaxy is related to mass, the greater the speed the greater the mass, the speed is too fast so the only explanation is mss that cant be seen by telescopes.
why must there be dark energy
no enough visible energy in the universe to account for the increasing expansion of the universe
the ………….. the wavelength the more energy objects are giving out
this causes them to emit a ……………… colour
shorter
blue
the hotter a star is the more radiation is emitted per unit time
