Expert: Scott A Wilson - 2/5/2011

Question
QUESTION: Are you able to assist me with these?

Find the x and y components for each of the following vectors?
1. 118 kg at 310 degrees

2. 25m/sec^2 at 210 degrees

ANSWER: 1. If 118 is the length of a line at 310 degrees, then that is in the 4th quadrant.
  The basic angle to use is 360 - 310 = 50; sin(50) = -y/118 and cos(50) = x/118.
  Using the two equations, x and y can be found.

2. Draw a line that is the hypotenuse of a triangle that has length 25.
  Note that 210 degrees is 30 degrees past 180, so x and y are both negative.
  That is, -x/25 = coss(30) and -y/25 = sin(30).


---------- FOLLOW-UP ----------

QUESTION: So on #1. My answer is X= 90.34 and Y= 75.85????
On #2 My answer would be X=21.65 and y = 12.5 ???

Answer
#1 The answer is almost right, but the x and y are flipped in the return answer.
This might be since I gave the value of y first whereas usually the value of x is given first.
Also, though the y value is negative.

To state it again in proper order, x = 75.85 and y = 90.39.
Note that on the y = 90.39, you had x instead, and it was 90.34.
Changing the 9 to a 4 or a 4 to a 9 is a common mistake.

#2 For this problem, we are looking acceleration, which can be negative.
Since 210 degrees is in the 3rd quadrant, both x and y are negative.
This means the answer is x = -21.65 and y = -12.5.