A box of mass ?=20.5 kg is pulled up a ramp that is inclined at an angle ?=19.0∘ angle with respect to the horizontal. The coefficient of kinetic friction between the box and the ramp is ?k=0.305 , and the rope pulling the box is parallel to the ramp. If the box accelerates up the ramp at a rate of ?=2.89 m/s2 , calculate the tension ?T in the rope. Use ?=9.81 m/s2 for the acceleration due to gravity.

An electron of kinetic en-
ergy 1.20 keV circles in a plane per-
pendicular to a uniform magnetic
field. The orbit radius is 32.7 cm. Find
(a) the electron’s speed, (b) the magnetic field magnitude, (c) the circling frequency, and (d) the period of the motion.

For problem 28.21 calculate the cyclotron period in nanoseconds using a cyclotron radius of 32.7 cm. 5 sig. figs.

2. Critique the following carbon mitigation wedge plan from the perspective of developing nations. Is this friendly to the growth of these nations? Make sure you completely dissect the plan with respect to cost, energy needs, and threat of famine. Your critique should be 100-words or less.

Consider a bicycle wheel, radius ? with rim of mass ? and axle of mass ?. The masses of the wheel’s thin spokes are so small that we will neglect them. Initially, the wheel is resting on a horizontal surface, and you hold its axle, a hand on each side of the wheel, so that it doesn’t tip over. At time ? = 0? you exert a horizontal force of magnitude ? on the axle so that the wheel begins to roll without slipping.

a) Determine the wheel’s speed when you have pushed it forward a distance ?.

b) Determine the magnitude of the friction force that the surface exerts on the wheel while you push it.

In detail, explain what role magnetism play in the 'Charge to Mass ratio of an electron' experiment performed by J.J. Thomson?

How can magnetism alter the expected results?

Why is it important for the electron beam to be perpendicular to all non-negligible magnetic fields?

A uniform 45 kg beam that is 4.35 m in length sticks out from a vertical wall. A lightweight cable connects the end of the beam to the wall, making an angle of 60.0° between the beam and the cable. A 65 kg worker stands on the beam a distance of 1.75 m from the wall. What is the tension in the cable?

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