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Learning Introductory Physics with Activities

Section 1.11 Practice - Vectors

Subsection Generic Vectors

Calculation 1.11.1. Two Vectors I.

In the following figure, the magnitudes of the vectors are |aβ†’|=8 and |bβ†’|=4.5. Assume that cβ†’=aβ†’+bβ†’ and dβ†’=aβ†’βˆ’bβ†’.
Figure 1.11.1. Two vectors.
Determine the magnitude of the vectors c→ and d→? What is the angle to each vector from the positive x-axis?
Answer.
c→: 3 at 109.6o
d→: 8.1 at 167.5o

Calculation 1.11.2. Two Vectors II.

In the following figure, the magnitudes of the vectors are |aβ†’|=5 and |bβ†’|=5. Assume that cβ†’=aβ†’+bβ†’ and dβ†’=aβ†’βˆ’bβ†’.
Figure 1.11.2. Two vectors.
Determine the magnitude of the vectors c→ and d→? What is the angle to each vector from the positive x-axis?
Answer.
cβ†’: 4 at βˆ’42.5o
d→: 8.87 at 227.5o

Calculation 1.11.3. Vector Contest.

Three vectors add together to equal 0.β€― One vector has magnitude 3 and points in the positive x-direction; a second vector has magnitude 5 and points at 120o from the positive x-axis. Determine the third vector as a magnitude and direction.
Answer.
4.4 at βˆ’97o

Calculation 1.11.4. Sums and Differences of Vectors.

Use the figure to determine a single vector that is equivalent to the given summation of vectors in each of the cases below.  (The notation PQ→ represents a vector pointing from point P to point Q.)
Figure 1.11.3. Four points.
  1. PQ→+QR→
  2. RP→+PS→
  3. QS→+PS→
  4. RS→+SP→+PQ→
Answer.
  1. PR→
  2. RS→
  3. QP→
  4. RQ→

Subsection Position and Displacement Vectors

Calculation 1.11.5. Punting a Football.

A kicker punts a football from the very center of the field to the sideline 42 yards downfield.  What is the magnitude of the net displacement of the ball in yards?
Tip.
A football field is 100 yards long and 55 yards wide.
Answer.
50.2 yards

Calculation 1.11.6. The Flying Saucer.

A certain flying saucer is initially located at a position rβ†’i=400x^+350y^ m.  After a few minutes it has moved to a location rβ†’f=650x^βˆ’800y^ m.  What is the displacement of the flying saucer? 
Answer.
Ξ”rβ†’=250x^βˆ’1150y^ m

Calculation 1.11.7. Waddling Pond.

A park has a circular pond with a radius of 100 m.  Benny starts at its westernmost point, then waddles counterclockwise around the pond until he is at its northernmost point.  What is the magnitude and direction of Benny’s change in position?
Answer.
141 m northeast

Subsection Apply

Activity 1.11.8. Math Review.

(a)
Consider the integral V=∫27x2dx.
1. Describe the meaning of each symbol and number in this expression.
2. Determine the value of V.
3. Sketch a graph that gives meaning to this integral.
4. If x is measured in meters, what are the units of V?
(b)
Use an integral to determine the area of the triangle shown below. What is the meaning of the infinitesimal in the integral you use?
Figure 1.11.4.
(c)
Use an integral to determine the area of the shape shown below, where the curve is a parabola with its vertex at the lower left corner.
Figure 1.11.5.

References References

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Practice activities provided by BoxSand: https://boxsand.physics.oregonstate.edu/welcome.