D. Finding resultants when
angle between forces =
90°
Ex 1 ) A 5.0 N force
pulls an object north while a 12 N
force is pulling the object west.
Find the resultant
|
Scale 1 cm = 1 N???
Two Methods
Method One
Graphical Method
(Draw It!!)
1. Draw vectors to scale
(1 N = 1 cm)
2. Make a parallelogram
Protractor 101
1. Use the Acute Angles Only 2. Use a ruler to
get accurate measurements
3. Draw diagonal (resultant)
4. Find magnitude & direction of vector
Parallelogram Method
Method Two
- Trig. and
Pythagorean
(More accurate)
1. Use a2
+ b2 = c2 (To find magnitude)
5.0 N2 + 12 N2
= R2
2. Tanq = Opp./Adj.
TanӨ
= 5.0/12
Ө = ?
Tan (5/12)
Inverse Tangent (5 /12)
13 N 22.6 ° N of W
Name that Direction
50 degrees N of E, 35 degrees N of W
65 degrees S of W, 80 degrees S of E
Video Instruction
showmethephysics.com
E. Equilibrant
- Balancing Force
Resultants &
Equilibrants
[HTML5]
Show Me The Physics
Video Instruction
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The
Equilibrant is always
equal in magnitude and opposite in direction to the resultant
[ Flash
]
If…
Resultant = 5 N 53° N of
W
Then…
Equilibrant =
5 N 53° S of E
Video Instruction
showmethephysics.com
Ex 2)
Concurrent forces
(acting together)
of 10. nt east and 10. nt south act
on an object.
Resultant & Equilibrant using
Trig.
& Pythagorean
Theorem
1. 10 N2 + 10 N2 = c2
c = 14 nt
2. R = 14 nt 45° S of E
Equilibrant = 14 nt 45° N of W
Let's go to the Videotape!
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