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 Jun 5th 2018, 09:35 AM #1 Junior Member   Join Date: Jun 2018 Location: Paraguay Posts: 4 identification of symbol Here is the formula in the screenshot figuring piston assembly inertia. piston assembly inertia = Reciprocating Mass * CRANK RADIUS * W^2*(COS(Wt)+(crank radius/rod length)*COS(2*Wt)) W=angular frequency (crank rotations in 1 second times 6.28) Wt=unknown CRANK RADIUS=piston stroke/2 Please identify the Wt (omega t) symbol. thanks Here's the screenshot:
 Jun 6th 2018, 04:43 PM #2 Physics Team   Join Date: Apr 2009 Location: Boston's North Shore Posts: 1,576 If omega refers to an angle then omega t refers to an amount the angle has been through in time t. Suppose omega is the angle a crankshaft has turned during time t. Then angle = omega t
 Jun 8th 2018, 09:58 AM #3 Physics Team     Join Date: Jun 2010 Location: Morristown, NJ USA Posts: 2,352 It seems that they are using the upper case Greek letter omega ( $\Omega$ ) for angular velocity, which is measured in radians/second. Multiplying by time (t) gives the angle of the crank at time t. The use of the upper case omega is a little unusual, but not unheard of; the lower case version of omega ($\omega$) is more commonly used for angular velocity. Pmb likes this.
Jun 8th 2018, 01:26 PM   #4
Physics Team

Join Date: Apr 2009
Location: Boston's North Shore
Posts: 1,576
 Originally Posted by ChipB It seems that they are using the upper case Greek letter omega ( $\Omega$ ) for angular velocity, which is measured in radians/second. Multiplying by time (t) gives the angle of the crank at time t. The use of the upper case omega is a little unusual, but not unheard of; the lower case version of omega ($\omega$) is more commonly used for angular velocity.
Thanks. I neglected to distinguish between the two omegas.

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