Mid Term Chapter 3 Flashcards
Someone claims that the absolute pressure and a liquid of constant density doubles when the depth is doubled. Do you agree explain.
No, the absolute pressure and a liquid of constant density. It does not double when the depth is doubled. It is the gauge pressure at doubles when the depth is doubled.
A tiny steel cube is suspended in water by a string if the length of the side of the cube of very small, how would you compare the magnitude of the pressures on the top of bottom and side surfaces of the cube?
Since pressure increases with depth, the pressure on the bottom surface of the cube is higher than that on the top. The pressure varies literally along the side faces. However, if the length of of the sides of the tiny cube suspended in water by string are very small. The magnitude of the pressure on all sides of the cube are nearly the same.
Express Pascals law and give a real world example of it
Pascal’s law states that the pressure applied to a confined fluid increases the pressure throat by the same amount. This is a consequence of the pressure in a fluid remaining constant in the horizontal direction. An example of Pascal‘s principle is the operation of the hydraulic car jack
Consider two identical fans, one Tal and the other on top of a high mountain running at identical speeds. How would you compare the rates and the rates of these two fans?
The density of air at sea level is higher than the density of air on top of a mountain. Therefore, the volume flu rate of the two fans running at identical speeds will be the same. But the mass flow rate of the fan at sea level will be higher.
What is the difference between gauge pressure and absolute pressure?
The pressure relative to the atmospheric pressures called the gauge pressure and the pressure relative to an absolute vacuum is called absolute pressure
Explain why some people experience, nose, bleeding, and some other experience shortness of breath at high elevations
Atmospheric pressure is the external pressure exerted on the skin decreases with increasing elevation. Therefore the pressure is lower at higher elevations as a result the difference between the blood pressure and the veins and the air pressure increases. Fish pressure imbalance may cause some thin walled veins, such as the ones in the nose to burst causing bleeding. The shortness of breath is caused by the lower air density at higher elevations and the lower amount of oxygen per unit.
Define the resultant hydrostatic force acting on a merge surface and the center of pressure
The result of hydrostatic force acting on a submerged surface is the resultant of the pressure forces acting on the surface. The point of application of this result force is called the center of pressure.
Someone claims that she can determine the magnitude of the hydrostatic force acting on a plane surface, submerged in water, regardless of the shape and orientation if she knew the vertical distance of the centroid of the surface from the free surface and the area of the surface. Is this a valid claim?
Yes, because the magnitude of the resulting force acting on the plane surface of a completely submerged body in homogeneous fluid is equal to the product of the pressure C at the centroid of the vertical surface and the area of the surface. The pressure at the central of the surface is. Pc = Patm +pghc where HC is the vertical distance of the centroid of the free surface of the liquid
A submerged horizontal flat plane is suspended in water by a string attached to the centroid of its upper surface. Now the plane is rotated 45° about an access that passes through at central. Discuss the change in the hydrostatic force acting on the top surface of this plane as a result of this rotation. Assume the plan remains submerged at all times.
There will be no change on the hydrostatic force acting on the top surface of the emerge, horizontal flat plane as the result of this rotation, since the magnitude of the resulting force acting on the plane surface of a completely serve, merged body and a homogeneous fluid is equal to the product of the pressure C at the centroid of the surface and the area of the surface
You may have noticed that dams are much thicker at the bottom explain my dams are built that way
Dams are built, much thicker at the bottom because the pressure force increases with depth, and the bottom part of the dams are subjected to the largest force
Consider a submerged curved surface. Explain how you would determine the horizontal component of the hydrostatic force acting on the surface.
The horizontal component of the hydrostatic force acting on a curved surface is equal in both magnitude and line of action to the hydrostatic force acting on the vertical projection of the curved surface.
Consider a submerged curve surface explain how you would determine the vertical component of hydrostatic force acting on the surface
The vertical component of the hydrostatic force acting on a curved surface is equal to the hydrostatic force acting on the horizontal projection of the curved surface plus or minus if acting in opposite direction, the weight of the fluid block
Consider a circular surface subjected to hydrostatic forces by constant density liquid. If the magnitude of the horizontal and vertical components of the resulting hydrostatic forces are determined, explain how you would find the line of action of this force.
The resultant hydrostatic force acting on a circular surface, always passes through the center of the circle since the pressure forces are normal to the surface, and all lines are normal to the surface of a circle pass through the center of the circle. That’s the pressure forces from a concurrent force system at the center, which can be reduced to a single equivalent force at that point if the magnitude of the horizontal and vertical components of the resultant hydrostatic force are known, the tangent of the angle, the resultant hydrostatic forces make with the horizontal is tan a= Fv/Fh
What is buoyant force? What causes it? What is the magnitude of the buoyant force acting on a submerged body is volume is free? What are the directions and the line of action of the point force?
The upper force of fluid exerts on an immersed body is called the buoyant force. The buoyant force is caused by the increase of pressure and fluid with depth. The magnitude of the buoyant force acting on a submerged body. Who is the volume is V is expressed as. Fb = pgV. The direction of the point forces upward and its line of action passes through the centroid of the displaced volume.
Consider two identical spiral ball submerged in water at different depths. Will the boy for acting on these two balls be the same or different explain.
The magnitude of the buoyant force acting on a submerged body whose volume is fee is expressed asF= pgV. Wishes independent depth therefore, the boy force acting onto identical, spherical ball submerge, and water at different depths is the same.
Consider 25 cm diameter spiral balls one made of aluminum. The other of iron submerged, and water with the blunt forces acting on these two balls be the same or different.
The magnitude of the buoyant forces acting on a submerged body is independent of the density of the body. Therefore, the buoyancy forces acting on the 5 cm diameter aluminum and iron ball submerged in water is the same
Consider a 3 kg copper cube and a 3 kg copper ball submerged in liquid. Forces acting on these two bodies be the same or different. Explain.
The magnitude of the buoyant forces acting on a submerged body is independent of the shape of the body. Therefore, the buoyancy forces acting on the cube and the sphere made of copper submerge in water are the same since they have the same volume.
Discuss the stability of a submerged and a floating body who center of gravity is above the center of buoyancy
A submerged body who center of gravity is above the center of buoyancy, which is the centroid of the displayed volume is unstable. But a floating body may still be stable when the center of gravity G is above the center of the centroid of the displaced volume shifts to the side to point B during a rotational disturbance while the center of gravity G of the body remains unchanged the point is sufficiently these two forces create a restoring moment and return the body to the original position
And what conditions can a moving body of fluid be treated as a rigid body
I’m moving body of fluid can be treated as a rigid body when there are no sheer stresses i.e. no motion between fluid layers relative to each each other in the fluid body
Consider a glass glass of water, one stationary, and the other, moving on a horizontal plane with constant acceleration, assuming no splashing or spilling occurs, which class will have the higher pressure at the front midpoint and back of the bottom surface
The water pressure at the bottom surface is the same for all cases since the acceleration for all four cases is zero
Consider a vertical cylinder containing partially filled with water. Now the cylinders rotated about its axis at a specified angular velocity, and the rigid body motion is established. Discuss how the pressure will be affected at the midpoint and at the edge of the bottom surface due to rotation.
The pressure at the bottom surface is constant when the class is stationary. For glass moving on a horizontal plane with constant acceleration water will collect at the back, but the water depth will remain constant at the center. Therefore, the pressure at the midpoint will be the same for both glasses. But the bottom pressure will be low at the front relative to the stationary glass and the back. Note that the pressure in all cases is the hydrostatic pressure which is directly proportional to the fluid height.
