Abeam of o - particles of energy 4 kev with a rate of 3x108 particles/s strikes a target, a 10- μm thick aluminum foil. a detector of cross-sectional area 400 mm2 is placed 0.6 m from the target in a direction at 60° to the beam direction. considering the scattering of a-particle on an al nucleus as the scattering on a fixed center, find the rate of detection of o-particles. (atomic mass of al-27 u, where 1 u = 1.66×10-27 kg; atomic number of al-13; density ofal p 1 ev = 1.6. 10-19., the constant kin the coulomb's law is k = 9.109 n m2/c) = 2.71p kg/m3; atomic number of α-particle is 2; e = 1 .6. 10-19 c;

What elements are found in the inner and out core of the earth? the correct layers of earth's interior from the top to the center? what is the unwanted material that is removed from a mine called? how much stronger is an earthquake that registers 5 on the richter as opposed to 2? what occurs at a convergence plate boundary? the majority of the the earth's rock what is the most common element found in the earth's crust? what element is found in pyrite that contributes to acid mine drainage? why must mining companies post bond prior to permitting? how are bacteria being used in treating effluent from mines? what is a problem of acid mine drainage in rivers and soils? what do tectonic plates move on? why is gold smelting so damaging? how are artesian wells formed? where is dammed water colder than the river it flows into? what is one of the problems of uncontained aqueducts? what is the largest use of industrial water? underground sand and gravel formations that can store water? what type of water test measure acidity? which type of water test for cloudiness from suspended solids? what water test measures the amount of calcium and magnesium? these are all problems of coal power plants all of the following are advantages of riparian lands along rivers what type of water would be the warmest and have the least amount of dissolved oxygen? the zone of aeration is

Afisherman notices that his boat is moving up and down periodically without any horizontal motion, owing to waves on the surface of the water. it takes a time of 2.20 s for the boat to travel from its highest point to its lowest, a total distance of 0.670 m . the fisherman sees that the wave crests are spaced a horizontal distance of 5.80 m apart. (a) how much is the wavelength? (b) find the period of the wave. (c) how fast are the waves traveling? (d) what is the amplitude a of each wave?

Compare the horizontal displacement of the two balls as they travel to the ground. what do you observe?