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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

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.

Increases