Why can or cannot perfectly elastic collisions ever occur in nature??

1. The second order fringe when 700 nm light falls on a double slit is
observed at a 15° angle to the initial beam direction. How far apart are
the slits? Ans: 5.41 x 10^-6 m

2. Light of frequency 6 x 10^14 Hz falls on a pair of slits that are 0.0002 cm
apart. The center of the slits is 50 cm from the screen. How far from the
central bright line will the first order line appear? Ans: 0.13 m

3. Monochromatic light falling on two slits 0.026 mm apart produces the
fourth-order line at a 6.4°angle. What is the wavelength of light used?
Ans: 7.25 x 10^-7 m

4. Light of wavelength 6.5 x 10^-5 cm passes through a single slit and falls on
a screen 100 cm away. The third-order dark band is 0.25 cm from the
center of the pattern. What is the slit width? Ans: 7.8 x 10^- 4 m

5. A diffraction grating with 760 lines per cm is used to form a diffraction
pattern. The first-order line is 3 cm from the central bright spot. The screen
is 80 cm away. What is the wavelength of light used? Ans: 4.93 x 10^-7 m

6. At what angle will 710 nm light produce a third order maximum when
falling on a grating whose slits are 0.0017 cm apart? Ans: 7.2°

A billiard ball is shot east at 2.80 m/s. A second, identical billiard ball is shot west at 1.20 m/s. The balls has a glancing collision, not a head-on-collision, deflecting the second ball by 90° and sending it north at 1.55 m/s. What is the angle that the velocity of the first ball makes after the collision, with respect to the east direction?

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