Motion & Mechanics

A:

Air is a fluid because the force needed to deform it depends on how fast it is deformed, not on how much it is deformed. This differs from a solid, where the force needed to deform it remains the same whether it is done quickly or slowly.

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  • Why do some objects float in water and others sink?

    Q: Why do some objects float in water and others sink?

    A: Objects comprised of material that is denser than water tend to sink; objects with a lighter density tend to float. Since air is lighter than water, hollow objects can float if their total density is less than water. Preventing objects from absorbing water is important.
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  • What is a non-Newtonian fluid?

    Q: What is a non-Newtonian fluid?

    A: Non-Newtonian fluids are those that behave differently than Newtonian fluids do with regard to viscosity. Typically, stress causes non-Newtonian fluids to alter their flow patterns or viscosity. The stress can cause the viscosity to increase or decrease, depending on the particular non-Newtonian fluid.
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  • What are pulleys used for?

    Q: What are pulleys used for?

    A: A pulley is a simple tool that can be used for many things, such as lifting heavy objects or to change the direction of applied forces for various means. A pulley is a very simple tool that consists of a wheel on a fixed axle that has grooves for keeping a rope or wire in place. This makes pulleys useful for lifting heavy objects using applied human force.
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  • What is the law of inertia?

    Q: What is the law of inertia?

    A: The law of inertia states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. The law of inertia is sometimes referred to as Newton's first law of motion.
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  • What is potential energy?

    Q: What is potential energy?

    A: Potential energy is defined as the energy possessed by a body due to its position or height above the surface of the Earth. Water stored in a dam has potential energy. This potential energy has the capacity to do work.
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  • What is water displacement?

    Q: What is water displacement?

    A: Water displacement is a particular case of fluid displacement, which is simply the principle that any object placed in a fluid causes that fluid to no longer occupy that volume of space. The fluid must go somewhere, however, and so with liquids in containers, this causes their overall height to rise. Gases are also fluids subject to displacement, and they both fill space and are compressible, so an object introduced to a sealed container full of a gas simply decreases the volume of the gas and increases its pressure.
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  • Why can't liquids be compressed?

    Q: Why can't liquids be compressed?

    A: Liquid compression is difficult but not impossible because they feature a mid-level intermolecular force that makes their molecules difficult to compress. Intermolecular force is the strength used to hold molecules tightly together or force them apart. The strength of the intermolecular force depends on the state of the matter, with solids having the strongest intermolecular force and gases having the weakest intermolecular force.
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  • What is the meaning of unbalanced force?

    Q: What is the meaning of unbalanced force?

    A: Unbalanced force occurs when two forces acting on an object are not equal in size, causing a change in motion. Unbalanced forces cause a still object to move or moving objects to slow down or speed up, stop or change direction.
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  • How do you measure the water flow through a pipe?

    Q: How do you measure the water flow through a pipe?

    A: The water flow though a pipe is measured by using a mechanical flow meter. These work through positive displacement, where the volume of water flowing though in a given amount of time is measured. Domestic areas typically use a piston/rotary positive displacement meters or a nutating disk meter, while commercial areas use turbine flow meters.
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  • What are types of potential energy?

    Q: What are types of potential energy?

    A: Potential energy is the stored energy of an object that has the potential to change to a different form of energy to do work. The types of potential energy are gravitational, elastic, chemical, electric and nuclear.
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  • How can friction be reduced?

    Q: How can friction be reduced?

    A: Friction can be reduced by adding a lubricant or by smoothing and polishing surfaces, according to the HyperPhysics program at Georgia State University. For some substances, smoothing only reduces friction to a point, after which friction increases with further smoothing.
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  • How does streamlining reduce air resistance?

    Q: How does streamlining reduce air resistance?

    A: Streamlining reduces air resistance by providing a smooth surface over which air flows easily and uniformly. Without streamlining, eddies formed on the trailing edges of objects create turbulent, low-pressure areas and increase air resistance, also known as drag.
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  • What is an example of kinetic energy?

    Q: What is an example of kinetic energy?

    A: Because any moving thing or object has kinetic energy, there are many examples of this energy type, including a ball dropping into water, a car in motion and a moving arrow. However, there are different types or forms of kinetic energy.
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  • How do you find velocity?

    Q: How do you find velocity?

    A: Velocity is found by dividing the total amount of space an object moved by a measurement of time and combining that with the direction it moved. Velocity is a vector, and speed is only part of this vector.
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  • What is kinetic friction?

    Q: What is kinetic friction?

    A: Kinetic friction refers to the frictional force of a moving object. If a force is being applied on a stationary object, friction is considered a static force until movement occurs.
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  • How did Isaac Newton die?

    Q: How did Isaac Newton die?

    A: Newton died in his sleep in London, England, on March 31, 1727, at the age 85. On the previous day, after suffering severe pain in his abdomen, Newton blacked out and never regained consciousness.
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  • What does "E=mc2" mean?

    Q: What does "E=mc2" mean?

    A: Albert Einstein's formula "E=mc2" means energy equals the mass of an object multiplied by the speed of light squared. His theory means that the mass of an object, no matter how small, can be transformed into a tremendous amount of energy.
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  • What are the main branches of mechanics?

    Q: What are the main branches of mechanics?

    A: The two main branches of mechanics are statics and dynamics. Static mechanics is the study of forces which are required to keep a body in equilibrium. Dynamics is the study of motion itself, and the forces producing it.
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  • What is the difference between balanced and unbalanced forces?

    Q: What is the difference between balanced and unbalanced forces?

    A: Balanced forces are forces that produce no change in motion, while unbalanced forces produce some type of acceleration. With balanced forces, any forces in a given direction are exactly matched by forces in the opposite direction. With unbalanced forces, the forces in one direction are greater than those in the opposite direction, resulting in a net force that produces acceleration.
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  • Why does wood float on water?

    Q: Why does wood float on water?

    A: Wood generally floats because it's less dense than the water it floats on. However, some woods are denser than water and will tend to sink.
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  • How does sound travel?

    Q: How does sound travel?

    A: Sound travels in waves from a transmitter to a receiver through a medium. The wave is produced by the vibration of particles in mediums such as gases, liquids and solids. Because sound requires a medium of interconnected and interactive particles, it cannot travel in a vacuum such as space.
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