Momentum U4 Flashcards
What are the conditions for an elastic collision
The kinetic energy of the collision is conserved
P=
Mv
Kinetic energy =
P^2/2m
1/2mv^2
What is the de broglie wavelength? What is the equation?
The de Broglie wavelength shows that an electron can have the properties of a wave as well as a particle at high speeds
Wavelength=h/p
Define an electronvolt
It is the energy gained by an electron across a potential difference of 1v
What is 1eV equal to
1.6x10^-19
What is the experiment to find rate of change of momentum (what is a key apparatus of this experiment)
The mass pulling a trolley over time using a motion censor
Change in momentum =
Force x time
What does the graph of momentum against time look like
It is directly proportional
What is the gradient equal to as the line on a momentum/time graph
Acceleration
Is momentum conserved? If so, when?
YES ALWAYS
What is an experiment to prove the conservation of momentum
The two trolleys colliding and having pieces of card ontop of each one cutting through light gates
Total momentum before =
Total momentum after
For rate of change of momentum what measurements do you take
Record the movement of the trolley over time as a force makes it move from rest, using a motion censor. This means you can find the velocity/second and consequently the momentum/second (because mass is known). Find the force by mg=F as a known mass is used to pull the trolley.
What must be kept constant for the rate of change of momentum experiment?
The force pulling the trolley so, the mass
What can you do to find a distance if it is at an angle (angle is known)
Resolve / use Pythagoras
What do you assume when considering conservation of momentum
There are no external forces acting
How would you find the masses of a neutron and a He nucleus colliding
The mass of a neutron would be taken as 1 and a helium nucleus has 4 neutrons so the helium would be taken as having mass of 4
Newton’s second law is
F=ma
Ek=
1/2mv^2
P^2/2m
What is the rate of change In momentum directly proportional to
Resultant force acting on an object
Is kinetic energy always conserved
No
If kinetic energy isn’t conserved why is this in a collision?
Because some of the energy in the collision will be transferred to sound or thermal energy
