More physics Flashcards
Momentum
P=mv
Momentum is mass times velocity.
It is a vector.
If you go twice as fast, how does this change your momentum?
How does it change your Velocity?
P=m2v so doubles your momentum
KE=1/2 m(2v)^2
so your KE increases by factor of 4
Impulse
Change in momentum:
Pf-Pi same as mvf-mvi
How dose bouncing affect impulse?
A bounce will double the impulse.
No bounce: Bounce:
Final V is 0 Final V =Initial V
Impulse = mvf-mvi
0-mvi = mvi -mvf-mvi= -2mv
So object that bounce will have more force
Conservation of momentum is calculated…
Conservation of momentum is calculated in each dimension. x axis and y axis.
conservation means equals zero
Elastic Collisions
Bounce/ no sticking, no deformation
momentum is conserved AND
KE is conserved, meaning KEf=KEi
Elastic collisions have the cheater equations she will provide
Inelastic Collisions
stick together, can have deformation,
thermal or sound energy lost
Momentum is conserved but KE is not!
When two objects stick together, their final momentum is equal (velocity is the same)
Myopia vs Hyperopia and treatment
Myopia-nearsighted. Rays are focused in front of the retina. correct with a diverging/concave lens
Hyperopia- farsighted. Rays are focused behind the retina. Correct with a converging/convex lens.
Resistors connected in series
Resistors connected in parallel
Series- Current (I) is the same throughout, Voltage is additive like Resistance.
Rtotal= R1+R2+R3…
Parallel- Current (I) is additive. Voltage is the same throughout.
1/Rtotal= 1/R1 + 1/R2+ 1/R3…
This is because of Ohms Law
V=IR
What equation is used to solve :
A wire has a resistance of 0.20Ω and a cross-sectional area of 5.00x10-5 m2. If the resistivity of the wire is 2.0x10-8 Ω.m, what is the length of the wire?
R=p (L/A)
R is resistance, p is resistivity, L is length, A is area.
answer: 5x10^2 m
Range equation
R= Vi^2 (sin2θ) / g
Vinitial squared times sin 2 theta all divided by gravity.
Mass is irrelevant in range. θ 45 will always give the maximum range, given sin(2*45)=sin90=1.
Diverging lenses have a (positive/negative) focal point
Diverging lenses have a negative focal point.
How to find the power of a lens
P= 1/f
f=r/2
where f is the focal point, which is half the radius of curvature.
The unit of this power is Diopter
As light moves between mediums, what remains constant?
The frequency will not change. It cannot or there would be a back log where is slows or nothing where it speeds up. Therefore, it cannot change.
In regards to snells law, when light is moving between mediums, what has to happen to θ if n goes down?
n1sinθ1 = n2 sinθ2
so if n goes down θ must go up to keep the equality.
Thin lens equation (mirror equation)
1/f = 1/do + 1/di
f is focal length
do is distance of the object
di is distance of the image. If solving for di and you get a negative number, implies virtual image.
In a plane mirror, what kind of image is formed?
Always a virtual upright image
Plane mirror will always have equal distance between object and image.
Magnification is always 1: meaning same size.
What kind of image does a concave mirror form?
depends!
Object distance (p) > focal distance (f) = upright and virtual
p < F = inverted and real
What kind of image does a convex mirror form?
always upright and virtual
always smaller image, not magnified.
ALWAYS A NEGATIVE VALUE FOCAL POINT
How do you find the focal distance for a mirror?
focal distance = 1/2 radius of curvature
Magnification
hi/ho= -(di/do)
l m l>1 =image is magnified
l m l<1 = image is minimized
if m is negative its inverted
if m is positive its upright
