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Showing posts from November, 2012

### Projectile Motion : Practice Problems + Solutions

Solve the following questions using what you know about projectile motion.
1.A roadrunner runs directly off a cliff with an initial velocity of 3.5 m/s. a)What are the components of this velocity? Vx = 3.5 m/s                            Vy = 0 m/s
b)What will be the horizontal velocity 2 seconds after the bird leaves the cliff? 3.5 m/s – horizontal velocity is unchanging
c)If the cliff is 300 m high, at what time will the roadrunner reach the ground? h = dy = ½ * 10 * t2 = 300 300 * 2 / 10 = t2 = 60 t = 7.75 s
d)How far from the cliff will this bird land? dx = 3.5 * 7.75 = 27.125 m
e)If there is a small pond which begins 25m away from the cliff and extends 2.5 meters from there; will the roadrunner land in the pond? Yes, the pond is from 25 m to 27.5 m, so the roadrunner will land in the pond.
f)What is the final vertical velocity at which the roadrunner is traveling? [The vertical velocity at the time when the bird reaches the ground] Vy = 10 * 7.75 + 0 = 77.5 m/s
g)What is the final horizontal vel…

### Chapter 6: Work and Energy

Practice Problems

1Just as a car tops a 38 meter high hill with a speed of 80 km/h it runs out of gas and coasts from there, without friction or drag. How high, to the nearest meter, will the car coast up the next hill?
2A pendulum has a mass of 3.6 kg, a length of 1.7 meters, and swings through a (half)arc of 29.4 degrees. What is its amplitude to the nearest centimeter?
3To the nearest tenth of a Joule, what is its maximum kinetic energy of the pendulum in problem 2?
4To the nearest tenth of a Joule, what is the total energy of the pendulum in problem 2?
5A 2 kg metal plate slides down a 13-meter high slope. At the bottom its speed is 9 m/s. To the nearest Joule, what was the magnitude of the work done by friction?
6If the slope in the above problem is 23 degrees, what is the coefficent of friction (to 2 decimal places)?
7An unstretched spring with spring constant 36 N/cm is suspended from the ceiling. A 3.6 kg mass is attached to the spring and let fall. To the nearest tenth of a c…

### Cosmic Rays

High energy electrons, protons, and complex nuclei can be produced in a number of astronomical environments. Such particles travel throughout the universe and are called cosmic rays. Some of these particles reach our Earth. As these objects hit our atmosphere, other particles called pions and muons are produced. These particles then slow down or crash into other atoms in the atmosphere. Since the atmosphere slows down these particles, the higher we travel, the more cosmic radiation we see. When you visit the mountains or take an airplane ride, you will encounter more cosmic radiation than if you stayed at sea level.
Most cosmic radiation is very energetic. It can easily pass through an inch of lead. Since cosmic radiation can cause genetic changes, some scientists believe that this radiation has been important in driving the evolution of life on our planet. While cosmic radiation can cause some damage to individuals, it also has played an important role in creating humans. Ou…

### Antimatter

In 1930, Paul Dirac developed the first description of the electron that was consistent with both quantum mechanics and special relativity. One of the remarkable predictions of this theory was that an anti-particle of the electron should exist. This antielectron would be expected to have the same mass as the electron, but opposite electric charge and magnetic moment. In 1932, Carl Anderson, was examining tracks produced by cosmic rays in a cloud chamber. One particle made a track like an electron, but the curvature of its path in the magnetic field showed that it was positively charged. He named this positive electron a positron. We know that the particle Anderson detected was the anti-electron predicted by Dirac. In the 1950's, physicists at the Lawrence Radiation Laboratory used the Bevatron accelerator to produce the anti-proton, that is a particle with the same mass and spin as the proton, but with negative charge and opposite magnetic moment to that of the proton. In order t…

### The Tao of Physics - F. Capra

Contents: I THE WAY OF PHYSICS 1 Modern Physics-A Path with a Heart? 17
2 Knowing and Seeing 26
3 Beyond Language 45
4 The New Physics 52
II THE WAY OF EASTERN MYSTICISM
5 Hinduism 85
6 Buddhism 93
7 Chinese Thought 101
8 Taoism 113
9 Z e n 121
III THE PARALLELS
10 The Unity of All Things 130
11 Beyond the World of Opposites 145
12 Space-Time 161
13 The Dynamic Universe 189
1 4 Emptiness and Form 207
15 The Cosmic Dance 225
16 Quark Symmetries-A New Koan! 247
17 Patterns of Change 261
18 Interpenetration 285