Try this at Home

You can do this with a ping pong ball and a hair dryer

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St. Mary's U. Astronomy and Physics Dept.



When a fluid, moves in a single direction, it exerts very little pressure perpendicular to the direction of its flow.
The external air pressure keeps the ball in place.

| Flash |



F. Resultants when angle between forces ≠ 90°


Ex) 5 N North & 3 N 30° S of E act concurrently (on a single point).


Find the resultant & equilibrant.




Angle not 90 degrees, can't use
Pythagorean theorem




Graphical Method



1. Draw vectors to scale




2. Make parallelogram





3. Draw diagonal (resultant)




4. Find magnitude & direction of vector



Graphical Method



1. Measure length, Convert to Newtons using scale  1 cm = 1 N



2. Measure angle vector makes with horizontal



R = 4.5 N 53° N of E




E = 4.5 N 53° S of W











Ranking Task

Rank the resultants from SMALLEST to LARGEST


Jan 2006






Monster Shoot Out Game
[ HTML5 ]

St. Mary H.S. Physics



AP Question

Hewitt Question


Ex) Relative to the ground, an airplane gains speed when it encounters wind from behind, and loses speed when it encounters wind head on.


When it encounters wind at a right angle to the direction it is pointing, its speed relative to the ground below

A. increases. 

B. decreases. 

C. is the same as if there were no wind.

D. Need more information.






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