One observer stand on a train moving at a constant speed, and one observer stands at rest on the ground. The person on the train stands at the back of the car and turns on a flashight; the light travels to the front of the car, bounces off a mirror, and returns to the back of the car (assume the light is traveling in a vacuum). the observer on the train measures the time it takes for the light to take this path and knowing the length of the car, calculates the speed of light. What value does he obtain?

a) Greater than c

b) Equal to c

c) Less than c

d) The speed of the light canot be determined without knowing the speed of the train

Ais useful when you need a simple machine to you separate two things. a. lever b. screw c. pulley d. wedge

Chapter 23, problem 075 the figure shows a geiger counter, a device used to detect ionizing radiation (radiation that causes ionization of atoms). the counter consists of a thin, positively charged central wire surrounded by a concentric, circular, conducting cylindrical shell with an equal negative charge. thus, a strong radial electric field is set up inside the shell. the shell contains a low-pressure inert gas. a particle of radiation entering the device through the shell wall ionizes a few of the gas atoms. the resulting free electrons (e) are drawn to the positive wire. however, the electric field is so intense that, between collisions with gas atoms, the free electrons gain energy sufficient to ionize these atoms also. more free electrons are thereby created, and the process is repeated until the electrons reach the wire. the resulting "avalanche" of electrons is collected by the wire, generating a signal that is used to record the passage of the original particle of radiation. suppose the radius of the central wire is 24 âµm, the inner radius of the shell 2.3 cm, and the length of the shell 14 cm. if the electric field at the shell's inner wall is 2.8 ă— 104 n/c, what is the total positive charge on the central wire?

What is created when solids,liquids,an gases mix with one another