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# Gravity

Gravity is a natural phenomenon in which all physical bodies are attracted to each other. It is commonly witnessed as the agent that gives weight to objects with mass and causes them to fall to the ground when dropped. It is also the same agent that allows your feet to stay on the ground.
Gravity is one four fundamental interactions of nature. The other three include electromagnetism, nuclear strong force and weak force. Gravitational force is the only fundamental force that affects all matter. This force is proportional to the masses of the interacting bodies.

The cosmological perspective of gravitation says it causes dispersed matter to coalesce matter to remain intact. This accounts for the existence of planets, galaxies, stars and most macroscopic objects in the universe. Gravity is also responsible for keeping the Planets in orbit around the sun.
Gravity is what keeps the moon in its orbit around the Earth. The moons gravitational pull is what influences the tides. This occurs by natural convection by the density gradient.

Every planet is surrounded by its own unique gravitational field. The gravitational field is numerically equal to the acceleration of objects under its influence. Earth’s acceleration due to gravity is 9.80665 m/s2 or 32.1740 ft/s2. This is ignoring air resistance.

### Lorentz transform of the components of the velocity

A photon moves at an angle θ with respect to the x' axis in frame S'. Frame S' moves at speed v with respect to frame S (along the x' axis). Calculate the components of the photon's velocity in S, and verify that the speed is c.

### Gravitational time dilation

Someone moves to the top of the World Trade Center in New York and moves back to the ground floor after one year according to a clock located at the ground floor. By how much did this person age?

### Converging Lens with Focal Length

See the attached file. 1. A converging lens with a focal length of 3.1 cm is used to image an object which is 3.4 cm away from the lens. How far from the lens is the image? 2. A light beam (initially in air) strikes a substance with an index of refraction of 1.4 at an incident angle of 18.0 degrees. What is the refracted a

### Acceleration Due to Gravity, Time and Horizontal Velocity

1. (PART ONE OF TWO): You drop a stone from a position of rest. How far will it fall vertically in the ?rst 5 s? The acceleration of gravity is 9.8 m/s. 2. ( PART TWO OF TWO): If you instead toss it horizontally at 1.6 m/s, how far will it fall vertically in the ?rst 5 s? 3. A cat chases a mouse across a 1.7 m high table.

### Centripetal acceleration, Angular speed and Tangential speed

1. When jumping straight down, you can be seriously injured if you land stiff-legged. One way to avoid injury is to bend your knees upon landing to reduce the force of the impact. A 80.4-kg man just before contact with the ground has a speed of 8.27 m/s. (a) In a stiff-legged landing he comes to a halt in 3.85 ms. Find the magn

### Energy and Gravity

See attached image for picture of problem. A particle P of mass m is fastened to the end of a string with length L. The particle starts from rest, in a position where the string is taut, and the direction of the string forms an angle of 60 degrees with the vertical. In the lowest point of the circular arc, the particle P hits

### Young's Modulus from the slope of the graph and find the error

Calculations: Young's Modulus The Cross section of the wire is 9.07 x 10 -8 m2 length = 0.877 m Net Load (g) Elongation 100 1.11.x 10-4m 200 2.15.x 10-4m 300 3.33.x 10-4m 400 4.37.x 10-4m 500 5.34.x 10-4m 600 6.23.x 10-4m 700 7.11

### Water flow rate through an opening in a tube

Please see attached file for the illustration. Tube B (full of air) is sealed on the top and a 16" OD opening on the bottom. B is 104.6' long. Container E (full of air) is inserted into section H and permanently fixed in place. B is inserted fully into container C. Water rises 59.6' into B. H is 45' feet of air. See Illus

### Simple pendulum period depends on length, amplitude, gravity

Consider an ideal pendulum consisting of a "bob" of mass m hanging from a light (massless) string of length L. The pendulum swings back and forth in simple harmonic motion (SHM). You may assume that the oscillations are small, so that the motion is "ideal" SHM. Which of the following statements are true? 1. If the string len

### Gravitation: 4 Problems

1) The following formula represents the period of a pendulum,T. T = 2π(l/g) (a) What would be the period of a 1.8 m long pendulum on the moon's surface? The moon's mass is 7.34 1022 kg, and its radius is 1.74x10^6 m. 2) A force of 40.9 N is required to pull a 10.2 kg wooden block at a constant velocity across a smooth gla

### Insterstellar Travel and Difficulties

Will it be possible in the future to travel to other stars ? What difficulties are there? Please use the web for suitable, supporting articles. - Provide references (do not use Wikipedia)

### 4 Physics multiple choice: satellite orbit, airplane downward dive, force on the moon,

1) Imagine a 560 kg satellite in a circular orbit around the earth with a period of 4.8 hours. (a) Determine the height of the satellite above the surface of the earth (b) Determine the speed of the satellite in m/s. (c) Determine the force of gravity on the satellite. Mass of Earth = 6.0 x 1024 kg Radius of Earth = 6.4 x

### Specific Gravity and Density

What are the units of specific gravity? Assuming that the density of water is 0.997 g.mL^-1 and the specific gravity of gold is 19.28 what is the density of gold in g.mL^-1? In pounds per cubic foot? my attempt: no units for specific gravity. Density of gold in g.ml^-1 = 19.2 g/mL^-1 I have no idea how to convert to pounds p

### Vertical motion under gravity

Please help with the following problem. You are standing on a balcony 30 feet off the ground. You want to throw your key to someone on the ground. You throw it angled upward with initial velocity of 55 ft/sec. assume that the acceleration due to gravity is -32 ft/sec/sec. A) find the position function in terms of time, t.

### Two problems: Dimensional analysis and Flow of fluid in pipe.

Please see attached file for full problem description. 1. The thickness h of a puddle of water on a waxy surface depends on the density ρ of the liquid, the surface tension γ (SI units: N/m) and another physically which is gravity, g. Use dimensional analysis to find a relationship between the thickness and the other 3 vari

### Falling objects Air resistance Gravity Gravitational force

Part 1, each question should be answered separately. 7. Suppose you are in a barrel going over Niagara Falls and during the fall you drop an apple inside the barrel. Would the apple appear to move toward the top of the barrel or toward the bottom, or would it remain stationary within the barrel? 10. (a) Imagine that Charlo

### Astrophysics: Friction, Potential Energy, and Kinetic Energy

1. A spring with k = 40.0 N/m is at the base of a frictionless 30.0° inclined plane. A 0.50-kg object is pressed against the spring, compressing it 0.20m from its equilibrium position. The object is then released. If the object is not attached to the spring, how far up the incline does it travel before coming to rest and then

### physics

Could you please provide the answers and workings out to the following physics problems. explain exactly how you came up with answer, provide a graph/drawing where needed for better understanding of the answer. Please see attachment. 1. When the net force that acts on a hockey puck is 10 N, the puck accelerates at a rate

### Spring Compression

A small block of mass 0.09 kg is placed against a compressed spring at the bottom of a frictionless track that slopes upward at an angle of 40* above the horizontal. The spring has k=640 N/m and negligible mass. When the spring is released, the block travels a maximum distance of 1.8 m along the track before sliding back down. B

### Earth, stars, and humanity's search for extraterrestrial intelligence.

Hello I'm of need with patrs A, C & D. Please make them at least 400 words each. I have done B, E & F. but after this help I'll also need to make a 20-25 slide powerponit which I will do. a. Describe the properties of life on Earth. (400 words) b. Examine the possibilities of extraterrestrial life in our solar system. Wh

### Ideal spring and simple harmonic motion

To measure the static friction coefficient between a 1.9 kg block and a vertical wall, the setup shown in the drawing is used. A spring (spring constant = 418 N/m) is attached to the block. Someone pushes on the end of the spring in a direction perpendicular to the wall until the block does not slip downward. If the spring i

### Acceleration of Gravity/Divergence Theorem

Acceleration of Gravity. See attached file for full problem description. Find the acceleration of gravity g for the following mass distribution. The mass distribution consists of an infinitely long "wire" of radius a running along the z axis, surrounded by empty space then by a hollow cylinder with inner radius b and outer ra

### Spacing of Rails/Removal of Heat

1. Segments of 12mt long steel rails are laid end to end when the temperature is -12 degree C. A space is left between rail segments to allow for thermal expansion. a. If they are to just touch when the temp is 33degree C, the spacing is --------- 2. A freezer has a coefficient of performance of 2.40 and can convert 1.80 k

### Reaction on point A

In problem 16.3(a), A 60-lb uniform thin panel is placed in a truck with end A resting on a rough hoirzontal surface and end B supported by a smooth vertical surface. Knowing that the deceleration of the truck is 12 ft/s^2, determine the reactions at ends A is a. 70.03 lb b. 60.30 lb c. 90.70 lb d. 80.71 lb

### The Moon is in orbit around the Earth. Is the moon pulled y the Earth's gravity: or is the Earth pulled by the Moon's gravity: or both. Explain.

The Moon is in orbit around the Earth. Is the moon pulled by the Earth's gravity; or, is the Earth pulled by the Moon's gravity; or, both. Explain.

### Average net force on the man during landing on the ground

A 75 kg man just before contact with the ground has a speed of 6.4 m/s. (a.) In a stiff-legged landing he comes to a halt in 2.0 ms. What is the average net force that acts on him during this time. (b.) When he bends his knees, he comes to a halt in 0.10 s. What is the average net force now? (c.) During the landing,

### Potential energy and chemical potential.

See attached file.

### Physics: Energy conversions, mechanical energy, elastic vs inelastic, initial speed, torques, energy required, angular speed, doppler effect

A ball dropped to the floor rises to a height less than its original height. Discuss some of the energy conversions that take place in a system like this. When a mass is placed on top of a vertical spring, the spring compresses and the mass moves downward. Discuss this system in terms of mechanical energy. Your car rolls

### Waves - What is the value of g, the acceleration due to gravity, on Planet X?

Astronauts visiting Planet X have a 2.40 m-long string whose mass is 5.50 g. They tie the string to a support, stretch it horizontally over a pulley 1.60 m away, and hang a 1.80 kg mass on the free end. Then the astronauts begin to excite standing waves on the string. Their data show that standing waves exist at frequencies of 6

### Circular Motion with Centripetal Acceleration

I need some help with circular motion physics questions: 1. Young David who slew Goliath experimented with slings before tackling the giant. He found that with a sling of length .598 m, he could develop a rotation rate of 8.04 rev/s in his weapon. If he increased the length to .892 m, he could revolve the sling only 5.99 time