Gases and liquids can flow which is what makes them fluids. Two examples are water and air.
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Distinguish between force and pressure.
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Pressure is the force acting on a unit area, while force is a push or pull that tends to change the shape, direction, and position of a body.
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What is the relationship between liquid pressure and the depth of a liquid? Between liquid pressure and density?
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The pressure from the fluid is directly proportional to the density of the fluid, as well as the height of the fluid above the datum line.
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If you swim beneath the surface in saltwater, will the pressure be greater than in freshwater at the same depth? Why?
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Yes, because the density of saltwater is greater than the density of freshwater and p∝d.
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How does water pressure 1 m below the surface of a small pond compare with water pressure 1 m below the surface of a huge lake?
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Pressure in both cases will be the same since p∝ height of fluid above datum line.
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If you punch a hole in a container filled with water, in what direction does the water initially flow outward from the container?
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The water will flow in a horizontal direction away from the container.
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Why does the buoyant force act upward on an object submerged in water?
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Because the weight of the object, that is the gravitational force on the object will be directed downwards. This weight on the water pushed the water downwards. So increase in the pressure of the water in the downward direction produces an upward force called buoyant force which acts on the object to counter balance its weight.
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Why is there no horizontal buoyant force on a submerged object?
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Buoyant force is force which is opposite the weight of the immersed object by fluid. The horizontal component of the weight of the object is zero, such that the horizontal component force opposite by the fluid also zero.
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How does the volume of a completely submerged object compare with the volume of water displaced?
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The volume of the completely submerged object is equal to the volume of displaced water.
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How does the buoyant force on a submerged object compare with the weight of water displaced?
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The buoyancy force is equal to the weight of the water displaced.
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Distinguish between submerged body and an immersed body.
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An immersed body may be either partially submerged or sully submerged, but a submerged body is always immersed.
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What is the mass of 1 L of water? What is its weight in newton's?
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Mass is 1 kg and weight in newton's is Fg=mg so 1(10)= 10
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If a 1 L container is immersed halfway into water, what is the volume of water displaced? What is the buoyancy force on the container?
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The volume of water displaced is 1÷2 L and the buoyant force is equal to the weight of the container.
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Is the buoyant force on a submerged object equal to the weight of the object itself or equal to the weight of the fluid displaced by the object?
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The buoyant force on a submerged object depends upon the weight of the fluid displaced by the object.
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There is a condition in which the buoyant force of an object does equal the weight of the object. What is this condition?
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If the object floats in the fluid, the buoyant force equals the weight of the object, and the net force is therefore zero.
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Does the buoyant force on a submerged object depend on the volume of the object or the weight of the object?
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The buoyant force on a submerged object depends upon the volume of the object.
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Fill in the blanks. An object denser than water will ¬¬¬¬_______ in water. As object less dense the water will _______ in water. An object with the same density as water will ______ in water.
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sink; float; neither sink nor float.
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How is the density of a fish controlled? How is the density of a submarine controlled?
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The density of a fish is controlled by the expansion and contraction of its air sacs while the density of a submarine is controlled by ballast tanks.
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It was emphasized earlier that buoyant forces does not equal an objects weight but does equal the weight of displaced water. Now we say buoyant force equals the object's weight, Isn't this a grand contradiction? Explain.
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This is not a contradiction in the case that the object is floating. When the object is floating on top of the water, the buoyant force must be equal to the object's weight, otherwise the net force would not be zero and the object would either be rising or sinking.
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Why do the caissons of the Falkirk Wheel have the same weight whether or not they carry boats?
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The Falkirk Wheel contains two balanced water filled caissons. The weight of the two caissons is the same. When boat enters the one of the caisson, the water leaving from the caisson is same. Due to this, the wheel will be balanced. So boat and water will not tip out from the wheel.
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What happens to the pressure in all parts of a confined fluid if the pressure in one part is increased?
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According to Pascal's Law, the pressure will be equally increased in all parts of the confined fluid.
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If the pressure in a hydraulic press is increased by an additional 10 N cm2, how much extra load will the output piston support if its cross-sectional area is 50 cm2?
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The pressure is 10 N cm2. P=F÷A| F=P×A|=10×50|=500 N
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What geometrical shape has the least surface area for a given volume?
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A spherical shape has the least surface area for volume.
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What is the cause of surface tension?
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Surface tension is caused by intermolecular attraction (attractive force between molecules).
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Distinguish between adhesive and cohesive forces.
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Forces between unlike substances are known as adhesive forces. Forces between like molecules are known as cohesive forces.
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What determines how high water will climb in a capillary tube?
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The bore of the capillary tube determines the height of the water. A smaller bore means that the liquid will be higher.
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