# Physics

Q:

## What is acceleration?

A:

Acceleration is any change in the speed or the direction of movement. It does not matter, from a scientific point of view, if only the direction changes but not the speed, as with a planet in a circular orbit, or if the object is reducing in speed but keeping the same direction. Acceleration, like velocity, is a vector quantity, so it can only occur in one direction.

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• #### Q:What is the purpose of a windmill?

A:

A windmill uses wind power to create rotational energy for the use in mills, pumps and presses. In the Netherlands, where windmills became important for local economies, they were used to make boards, paint, oil, paper and bread.

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• #### Q:Why does a bouncy ball bounce so high?

A:

Bouncy balls bounce high because the material of the ball is extremely elastic and can convert the kinetic energy from the fall into potential energy and back again with very little loss in momentum. Bouncy balls are used in many physics classrooms because they aptly demonstrate conservation of momentum through a highly elastic collision.

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• #### Q:What is the difference between kinetic and potential energy?

A:

Kinetic energy is contained in a moving object, while potential energy exists in a stored form. Potential energy can be changed into kinetic energy. Potential energy is ready for release, while kinetic energy is already doing work. The property of a body determines the type of energy it contains.

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• #### Q:What are examples of noncontact forces?

A:

Electricity, gravity and magnetism are all examples of non contact forces. A force is anything that can cause a physical change in an object.

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• #### Q:What are the parts and functions of a theodolite?

A:

A thedolite is an instrument used to measure horizontal and vertical distances using lenses and lines. They include several components, such as a telescope, a leveling mechanism, a tripod and a compass. Theodolites are used for surveying and construction to obtain precise readings of landforms so construction projects remain level and plumb with the ground.

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• #### Q:Does light always travel at light speed?

A:

Light typically travels at 186,000 miles per second, but scientists have found a way to slow it down to 38 miles per hour. A team at the Rowland Institute for Science has found a new state of matter to help slow light down. Sodium atoms were cooled almost to absolute zero, which is 459.67 degrees Fahrenheit below zero. That’s lowest temperature theoretically possible. They then shot a laser through the extremely cold sodium atoms, which acted like “optical molasses” to slow down the beam of light.

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• #### Q:What are the Laws of Attraction and Repulsion?

A:

The Law of Attraction is the belief that a person's thoughts attract specific things, people and situations into his life. The Law of Repulsion is the belief that the more a person thinks about what he does not want, the more he attracts what he does want. According to SelfGrowth.com, both beliefs support the idea that what a person thinks about, negative or positive, can manifest into reality.

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• #### Q:What were the contributions of Archimedes to the field of physics?

A:

The first-century inventor and scientist Archimedes is remembered by physicists as the originator of the principles of mechanics, buoyancy, the lever and the pulley, according to Famousscientists.org. Perhaps his best-known contribution to physics is his discovery of the principle of displacement, which states that objects displace a volume of water equal to their own weight.

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• #### Q:How does a fulcrum work?

A:

A fulcrum is the fixed support or pivot point for a lever, which is a simple machine used to overcome resistance. The lever is a stiff rod or bar, and the location of the fulcrum determines the class of the lever. Levers are useful to increase force, increase speed or change direction of a force, according to HowStuffWorks.

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• #### Q:What is the difference between an atomic bomb and a nuclear bomb?

A:

Although both atomic and nuclear bombs derive their immense power from reactions that take place in the nucleus of the atom, they do so in different ways. As the terms are most commonly used, an atomic bomb derives its energy from fission, or splitting atoms, while a nuclear device, or "H-bomb," is driven by fusion.

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• #### Q:How are mass and weight related to each other?

A:

Mass and weight are closely related because mass affects the weight of an object experiencing the effects of gravity. Weight is the measure of the force of gravity on an object's mass, while mass is the measure of how much matter there is in an object.

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• #### Q:What is the formula for tension in physics?

A:

In physics, the tension on a suspended object said to be equal to the weight of the object plus or minus the mass of the object times the acceleration acting on it. In other words, this is the weight of the object plus or minus the force on it, depending on the direction in which the force is acting.

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• #### Q:Why does rubbing your hands together make them warmer?

A:

Friction causes the hands to warm up when rubbed together. The greater the amount of friction between two objects is, the more heat is generated.

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• #### Q:How does gravity affect humans?

A:

Humans evolved with gravity, and gravity affects human physiology and general health. Studies show that weightlessness has a number of negative health effects. Finding ways to mitigate these dangers is essential for long-distance space travel.

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• #### Q:What are some good lab experiments that explain centripetal force?

A:

One good experiment that explains centripetal force is the spinning penny. A penny is put inside a balloon, and the balloon is filled with air. Then, the balloon is swirled around until the penny rolls around inside of the balloon. The penny continues to spin even after the swirling stops.

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• #### Q:How does an echo occur?

A:

An echo occurs when a sound wave reflects back towards its source after hitting a hard surface. Although the surface may absorb some of the sound, the remaining sound that is not absorbed continues moving, creating additional echoes by bouncing off surrounding objects until the sound is completely absorbed or dissipates.

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• #### Q:How are electromagnetic waves formed?

A:

Electromagnetic waves form from the vibrations of electric and magnetic fields. Unlike mechanical waves, electromagnetic waves do not need a medium to propagate, allowing them to travel through air, solids and even outer space.

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• #### Q:What is magnetic levitation?

A:

Magnetic levitation is a method of supporting an object with the repulsive force of magnets and the stability of servomechanisms. The object is thus suspended in the air, counteracting the effects of gravity.

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• #### Q:What is the definition of hydraulic pressure?

A:

The definition of hydraulic pressure is that of a force per unit area that is measured in pounds per square inch (PSI). Dynamic pressure and static pressure are the two pressure components.

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• #### Q:What is the definition of input force?

A:

Input force is the initial force used to get a machine to begin working. Machines are designed to increase the input force for a larger output force.

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