Gravity

February 19, 2003, 15:20

If X-Z axis is in horizontal plane and +Y axis is upwards( gravity is in -Y axis). Now if the flow is in -Y direction what shud be the value of 'g'?? Is it -9.81 or +9.81??? Does the value of gravity depends on the direction of flow or it depends on the orientation of the coorodinate axis??

February 20, 2003, 04:11

Gravity depends only on the orientation of the coordinate axis.

February 20, 2003, 20:01

If my model is drawn such that flow is in +Y direction and hence g =-9.81m/s^2. Now I rotate the model and the axis by 180 degrees such that the flow is again in +Y axis but the difference is that +Y axis is now pointing down in the direction of gravity. Would g=+9.81 in this case?????

February 21, 2003, 13:45

yes I guess,

it should be +9.81, in case you rotate the model about 180 degrees, since the flow is now towards the -Y direction which adds aditionally the gravitational force to the original acceleration of the flow.

-mp

February 19, 2003, 15:20	Gravity	#1
Pravir Kumar Rai Guest Posts: n/a	If X-Z axis is in horizontal plane and +Y axis is upwards( gravity is in -Y axis). Now if the flow is in -Y direction what shud be the value of 'g'?? Is it -9.81 or +9.81??? Does the value of gravity depends on the direction of flow or it depends on the orientation of the coorodinate axis??

February 20, 2003, 04:11	Re: Gravity	#2
ff Guest Posts: n/a	Gravity depends only on the orientation of the coordinate axis.

February 20, 2003, 20:01	Re: Gravity	#3
Pravir Kumar Rai Guest Posts: n/a	If my model is drawn such that flow is in +Y direction and hence g =-9.81m/s^2. Now I rotate the model and the axis by 180 degrees such that the flow is again in +Y axis but the difference is that +Y axis is now pointing down in the direction of gravity. Would g=+9.81 in this case?????

February 21, 2003, 13:45	Re: Gravity	#4
madasu Guest Posts: n/a	yes I guess, it should be +9.81, in case you rotate the model about 180 degrees, since the flow is now towards the -Y direction which adds aditionally the gravitational force to the original acceleration of the flow. -mp

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