I know that the type 1A Supernova stars are ideal to measure distances and to prove that the universe is accelerating.

They are standard candles type of stars. Their luminosity will decline after explosion.  They shine as brightly as an entire galaxy for a few weeks or months then gradually fade away.

By analyse the velocity obtained by the redshift and the distance the star is from us we can assume that the universe is accelerating.  But if I know the velocity and the distance, still how can I conclude the universe is accelerating? Plus, what this has to do with dark matter? And is the Universe gonna stop expending eventually?

I hope someone can help me with a clear explanation.

A thin film of oil (n = 1.28) is located on smooth, wet pavement. When viewed from a direction perpendicular to the pavement, the film reflects most strongly red light at 640 nm and reflects no light at 427 nm. What is the minimum thickness of the oil film?
nm

In warehouses, boxes get lifted up and down a lot, which is usually done by a forklift. A forklift has a maximum load it can handle so you need to know the force acting on the fork. As an example assume that you want to lift two heavy boxes with a forklift. The lower box A has a mass of 150 kg and the upper box B has a mass of 100 kg. Use g = 9.8 ?/?2

a) What is the magnitude of the force (in Newtons) that the forklift exerts on the lower box A while the boxes are moving up at constant speed?

b) What is the magnitude of the force (in Newtons) that the upper box B exerts on the lower box A while the boxes are moving up at constant speed?

c) The forklift has just picked up the boxes off the ground. What is the magnitude of the force that the forklift exerts on box A while the boxes move up and speed up with an upward acceleration of ?=0.5?/?2 ?

d) Assume that the forklift has picked up the boxes from a high shelf and is lowering them to the ground. What is the magnitude of the force the upper box exerts on the lower box while the boxes are slowing down at a rate of ?=0.5?/?2

1) Suppose after charging a 5.8

A fan is designed to last for a certain time before it will have to be replaced (planned obsolescence). The fan only has one speed (at a maximum of 650 rpm), and it reaches the speed in 2.0 s (starting from rest). It takes the fan 7.0 s for the blade to stop once it is turned off. The manufacturer specifies that the fan will operate up to 1 billion rotations. Andre lives in a hot climate, works outside of the home from approximately 8:00 am to 5:00 pm, Monday through Friday, does not own an air conditioner, and can't sleep with the fan running. Estimate how many hot days ?hot Andre will be able to use the fan, rounded to the nearest day.

Solve the following ordinary differential equations by separating variables and integration.
1. y'sinx=ylny, the boundary condition (b.c.) is that the function passes through (y=e,x=pi/3)
2. y'+2xy2=0, b.c. (y=1;x=2)
3. y'-xy=x, b.c. (y=1;x=0)

atoms with angular momentum s=1 is sent through a Stern-Gerlach apparatus oriented in the z (represented as SGz) direction and only the mz = 0 atoms are allowed to go through other sides.

1. Calculate the output at SGx

2. suppose one state (I 1 -1 > )x emerges . What happens if these beams are sent through SGz

A negative charge of –40nC exerts an attractive force of 12N on a second charge that is 0.050m away. What is the second charge?

What is the difference between induction and charging by conduction?

A charge of uniform linear density 2.20 nC/m is distributed along a long, thin, nonconducting rod. The rod is coaxial with a long conducting cylindrical shell (inner radius = 4.00 cm, outer radius = 9.00 cm). The net charge on the shell is zero. (a) What is the magnitude of the electric field at distance r = 13.0 cm from the axis of the shell? What is the surface charge density on the (b) inner and (c) outer surface of the shell?

When you take a bath, how many kilograms of hot water (47.3 °C) must you mix with cold water (13.3 °C) so that the temperature of the bath is 36.0 °C? The total mass of water (hot plus cold) is 195 kg. Ignore any heat flow between the water and its external surroundings.

Coherent electromagnetic waves with wavelength λ=500nm pass through two identical slits. The width of each slit is aa, and the distance between the centers of the slits is d=9.00mm.

a.What is the smallest possible width aa of the slits if the m=3 maximum in the interference pattern is not present?

b.What is the next larger value of the slit width for which the m=3 maximum is absent?

If you were conducting the wire/compass experiment (Part A) near the equator instead of in Oregon, would it be necessary to use more or less wire current to cause the compass needle to deflect? (This is related to the dip angle) Explain why.