Lift Force Question

[Dr Gerrard]

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All right, so I was doing the EK 30-minute exam from lecture 5, and I came across this.

"Lift force is directly proportional to the difference in pressure above and below the ball."

Pa + 1/2 * rho * va^2 = Pb + 1/2 * rho * vb^2

Where the a subscript is above and the b subscript is below.

So Pb-Pa = 1/2 * rho * va^2 - 1/2 * rho * vb^2

Now intuitively, this makes sense. However, in passage 3, EK just has deltaP, which they say represents the difference in pressure above and below the ball, which would mean Pa-Pb.

This last sentence does not make sense intuitively, as it is saying that a higher pressure above the ball would lead to a higher velocity above the ball which would cause a downward force.

So basically, is it a typo in the passage where EK says the above quoted sentence?

 

[Dr Gerrard]

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[Bernoull]

All right, so I was doing the EK 30-minute exam from lecture 5, and I came across this.

"Lift force is directly proportional to the difference in pressure above and below the ball."

Pa + 1/2 * rho * va^2 = Pb + 1/2 * rho * vb^2

Where the a subscript is above and the b subscript is below.

So Pb-Pa = 1/2 * rho * va^2 - 1/2 * rho * vb^2

Now intuitively, this makes sense. However, in passage 3, EK just has deltaP, which they say represents the difference in pressure above and below the ball, which would mean Pa-Pb.

This last sentence does not make sense intuitively, as it is saying that a higher pressure above the ball would lead to a higher velocity above the ball which would cause a downward force.

So basically, is it a typo in the passage where EK says the above quoted sentence?

The passage doesn't say or imply where Pressure is higher or lower, I think ur reading this into the passage. The text in blue is not in the passage, difference just means difference (either Pa-Pb or Pb-Pa), the diagram in the passage has higher v above and lower v below, the former correlates with lower pressure n the latter with higher pressure so lift is upwards.
I don't see any typo..