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Questions relating to motion in a plane

by pharm89
Tags: motion, plane, relating
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Dec29-06, 09:52 PM
P: 32
1. The problem statement, all variables and given/known data

I just would like to know if I'm using the right procedure to solve these problems.

(a) Suzanne is skiing with a velocity of 18.0 m/s (N30.0 degrees W). What is the (N) component of her velocity vector?

(b) TIm is running cross-country at 6.4 m/s (S) when he completes a wide turn and continues at 5.8 m/s (W). What is his change in velocity?

2. Relevant equations
Cos(theta) = adjacent / hypotenuse

velocity = V2 - V1
use of Pythagorean theorum formula

3. The attempt at a solution

(a) Given:
velocity = 18.0 m/s
30 degrees

Required: Vn

cos(theta) = adjacent/hypotenuse
Cos30 degrees = Vn / 18 m/s
Vn = (18.0 m/s) (Cos30 degrees)
=15.6 m/s

(b) Given:
V1 = 6.4 m/s (E)
V2 = 5.8 m/s W

Required: change in velocity

Analysis: velocity = V2 - V1
=V2 + (-V1)
=V2 - V1

use the pythagorean theorum to determine the magintude of the velocity vector.
V^2 = (5.8)^2 + (6.4)^2
=33.64 + 40.96
=74.6 m^2 s^2
=8.64 m/s

Then determine the direction of the velocity vector.
Tan (theta) = 5.8 m/s / 6.4 m/s =0.91
=42.3 degrees

Therfore his change in velocity is 8.64 m/s (S 42.3 degrees W)

Any help is always appreciated.
Pharm 89
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
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Dec30-06, 05:12 AM
P: n/a
Your solution is right.

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