Question

A woman leaves home and walks 3 mi. west, and then 4 mi. south. What is the magnitude of her displacement? Note: they are not asking you to add how far she went west and south. They are asking how far she is from home if she went directly back. Think of a triangle.

Answer 1

Vector Review Practice Answers:

1. B - initial (14,-5); terminal (0,0)

2. A - sqrt(22^2 + 4^2)

3. B - <4,12>

4. D - Yes, the two vectors have the same magnitude and direction.

5. D - Vectors u and v are neither because the angle between the two vectors is not equal to 0 degrees, 90 degrees, or 180 degrees

6. C - approximately 4 mi. at a direction angle of 56 degrees northeast

7. A - approximately 174 mph at a direction angle of 58 degrees northeast

8. A - -200

9. D - W = 59 ft*lbs

10. C - u = 4/5i - 3/5j

Answer 2

• 5 miles

Explanation:

The route makes a right triangle with legs 3 mi and 4 mi, and the hypotenuse of x mi.

Use Pythagorean to find the distance:

• x =
  `√(3^2 + 4^2)`
• x =
  `√(25)`
• x = 5 miles