An umbrella tends to jerk upward on a windy day principally because
A)air gets trapped under the umbrella,which warms,and rises.
B)buoyancy increases with increasing wind speed.
C)air pressure is reduced over the curved top surface.
D)all of the above

Question

Quizplus · Accepted Answer

The curved surface of an umbrella reduces the air pressure above it, creating a pressure gradient between the upper and lower surfaces. The higher air pressure below the umbrella pushes it upward, causing the jerking motion when subjected to the force of the wind. A and B are not correct because they do not explain the physics behind the upward movement of the umbrella.

An Umbrella Tends to Jerk Upward on a Windy Day