Mechanics Of Materials Assignment No.1

43Sir.Adnan Hanif

February 24, 2015

Define Pressure? Is Pressure a Scalar or Vector Quantity? Briefly elaborate your Answer?

1 PressurePressure (symbol: p or P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed.

Pressure is a SCALAR QUANTITY.

2 ReasonTake a look at the equation:

P = FA

dF = PdA1

We can assume that If P is vector then normal vector of areasurface & P would be to eachother.So there exists a dot product between P & A & if this is true then F should be scalar,hence our assumption that Pis a vector proves wrong.Moreover the pressure always acts surface so although in a sense we can say that pressure acts perpen- dicularly but yet we cannot say that it is a directional qty. its rather related to the orientation of surface.

1negative sign indicates unit vectors of force & area are parallel but opposite

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