Weather wind math

[dback42]

Will a bridge chair held down by a 20 litre bag of soil hold in 30-40 km/h winds?

[Wulf]

Will a bridge chair held down by a 20 litre bag of soil hold in 30-40 km/h winds?

How heavy is the soil, how 'aerodynamic' is the chair an which way is the wind blowing

[dback42]

How heavy is the soil, how 'aerodynamic' is the chair an which way is the wind blowing
soil is garden, fairly light chairs, wind coming from the east apparently, my prop is facing north south along University Ave. How many and how big should the holes be in the sign. I'll have six chairs each with a bag underneath holding them down, the sign made up of two pieces 8ft long will be tied to the chairs.

http://weathernetwork.com/weather/cities/can/Pages/CAON0696.htm