Because it has been decided that the right and upwards directions in a plane are the positive directions and the left and downwards are negative. Originally, the decisions were arbitrary but conventionally agreed (in the same sort of way that North is usually shown at the top of a map).
Any displacement in a positive direction is called a positive displacement.
Indeed it is.
They are the locations where the amplitudes of the two waves combine destructively. The positive displacement of one wave is exactly matched by the negative displacement of the other so that the overall displacement is zero.
It is called the displacement in the horizontal direction.
replacing equal quantity of liquid from cavity is called positive displacement. let understand it by an example : lets assume you fill a bath tube up to the very top - there is no room for anything else. Then step in the bath. What happens? Water flows over the sides onto the floor - right? That is positive displacement! The amount of water that comes out is exactly the volume of your foot and leg.
Non-positive displacement has slippage inside the pump and it is a continous, variable flow. But positive displacement has no slippage inside the pump, and it is a constant flow.
yes.only positive displacement pumps can be used in hydraulics
because they deliver a fixed quantity of the discharge irrespective of their rpm
A positive displacement pump causes a liquid or gas to move by trapping a fixed amount of fluid or gas and then forcing (displacing) that trapped volume into the discharge pipe. Positive displacement pumps can be further classified as either rotary-type (for example the rotary vane) or lobe pumps similar to oil pumps used in car engines.Moreover,these pumps give a non pulsating output or displacement unlike the reciprocating pumps and hence are called positive displacement pumps
positive displacement pump
Indeed it is.
The rate of displacement of a body is called its velocity.
Yes. If the slope is positive, the direction of the displacement is positive (e.g. north, east, or right). If the slope is negative, the direction of the displacement is negative (e.g. south, west, or left).
Well it is very important factor in fluid mechanics. The term comes often in compressors and Pumps. Displacement means change of place( Fluid ), Positive displacement means at all points of operating the discharge will be the same where as the discharge in non positive displacement varies at various operating points. For clear idea on the above compare the reciprocating pump with centrifugal pump at various operating points (by throttling) discharge valve).