What theoretical explanations exist for the fact that there are three generations of leptons and quarks?

I'm not so much asking why there are exactly 3 generations, but rather what makes electron, muon and tau differ. Also, since the three families of quarks don't have to be a priori related to the three families of leptons, I'm interested in answers for either quarks, leptons, or both.

3. A cube of Brass (B = 70 GPa) measuring 1.0 m on each side is submerged under water. It is lowerd to a depth where a force "F" is acting perpendicularly into each side, reduces the cube's volume by 1.8 %.

(a) Calculate the size of this force.

2.A researcher examines a piece of fresh human cartilage, with an area of 1.9 cm2. She observes that when subjected to a tensile force of 194 N it stretches by 4.8 %.

(a) Calculate the elastic modulus of cartilage.

1. A student pushes on the end of a helical spring, which in turn presses a 1.25 kg, wooden block onto a vertical wall. The coefficient of static friction between the block and wall is 0.5. She compresses the spring 5.2 cm.

(a) Calculate the minimum spring constant necessaary to prevent the block from sliding down the wall.

1. Explain the physical reason that this change in Planck's expression avoided the ‘Ultraviolet Catastrophe’.

2. Calculate the probability of finding the particle within the finite wall of the box when the particle is in the lowest and highest bound energy states of the box with one finite wall described above. Assume that the coefficient D is approximately D= (2/L)^1/2

Every second at a particular waterfall, some 6996 m³ of water falls a distance of 37 m. What is the increase in entropy in kJ/K, per second due to the falling water? (Assume a 23°C environment).

part a ) A person throws an object with mass m nearly vertically with an initial momentum p=(px,py,pz). With respect to the cartesian coordinate system where the person is looking in the direction y, with x directed to their right. Let ∝ be the elevation angle of the initial momentum (with respect to the x-y plane) and let θ be the angle of the initial momentum with respect to the y-z plane. Write parametric equations for the trajectory of the center of mass of the object.

part b) How high would the object need to be thrown if three objects are to be juggled at 120 beats per minute (each object is thrown in turn one at a time and one per beat) with a horizontal displacement of approximately 0.30 m? use g = 9.81.

what is the discussion and conclusions for the trajectories physics lab?

A shot putter threw a shot at an angle of 43o above the horizontal from a height of 2.0 m above the ground. The shot traveled 19.0 m horizontally from the launch position. (a) What was the initial speed of the shot when it left the shot putter’s hand? (b) How long was the shot in the air? {13.0 m/s, 2.0 s}

OSHA, the Occupational Safety and Health Administration, has established shandards for workplace exposure to noise. According to OSHA's Hearing Conservation Standard, the permissible noise exposure per day is 93.0 dB for 4 hours or 103 dB for 1 hour. Assuming the eardrum is 9.5 mm in diameter, find the energy absorbed by the eardrum, when subjected to each of these conditions.

(a) 93.0 dB for 4 hours

(b) 103 dB for 1 hour

(c) Is OSHA's safety standard simply a measure of the amount of energy absorbed by the eardrum?
Y or N
Explain.

The position of a particle is given by x = 1/3t3 - 2t2 and y = 1/2t2 - 2t. Positions are in meters and time is in seconds. Complete the following table. θ is the angle between v and a, dv/dt is the rate at which the speed is changing, and R is the radius of the trajectory's tangent circle.

1)During a thunderstorm, a lightning "bolt" carries current between a cloud and the ground below. If a particular bolt carries a total charge of 39 C in 1.2 ms, what is the magnitude of the current?
A

How many electrons are involved in this process?
electrons

A cart of mass m1 = 11 kg slides down a frictionless ramp and is made to collide with a second cart of mass m2 = 24 kg which then heads into a vertical loop of radius 0.25 m (a) Determine the height h at which cart #1 would need to start from to make sure that cart #2 completes the loop without leaving the track. Assume an elastic collision. (b) Find the height needed if instead the more massive cart is allowed to slide down the ramp into the smaller cart.

A Parasail rider wants to reach the maximum height allowed by the Federal Aviation administration... A Parasail rider wants to reach the maximum height allowed by the Federal Aviation administration if the rider’s boat is to tow the parachute at 30 miles per hour. How should the tow to reach the maximum flying height? A. Draw and label a diagram to represent this situation. B. Explain two different methods to solving this problems Method 1: Method 2: C. Find the length of the tow line using both methods from part (b) Write a “ rule of thumb” that does not require trigonometry for calculating the maximum height of a parasail rider given the length of the tow line?

A spring-loaded gun fires a 0.080-kg puck along a tabletop. The puck slides up a curved ramp and flies straight up into the air.

(a) If the spring is displaced 24.0 cm from equilibrium and the spring constant is 875 N/m, how high does the puck rise, neglecting friction?

x = m

(b) If instead it only rises to a height of 5.00 m because of friction, what is the change in mechanical energy?
W_nc =

A positive charge 1.1X10^-11 C is located 10^-2 m away from a negative charge of the same magnitude. Point P is exactly half way between them --what is the E field at point P?