AnswersPrecalculusDot Product and Work

Dot Product and Work — Unit test Answers

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Vectors u and v have magnitudes of 20 and 13, respectively, and the angle between them is 210°. What is the scalar projection of u onto v?

A
–17.32
B
–11.26
C
11.26
D
17.32
2
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Given vectors u = ⟨3, 4⟩ and v = ⟨4, 3⟩, what is the measure of the angle between the vectors?

A
0°
B
16.3°
C
163.7°
D
Undefined
3

Let v = ⟨–13, 2⟩ and w = ⟨–9, –5⟩. What is w – v?

A
⟨–22, –23⟩
B
⟨–4, 7⟩
C
⟨4, –7⟩
D
⟨22, 3⟩
4

Air traffic controllers are watching two planes on radar to ensure there is enough distance between them. Plane A took off at 10:00 a.m., and plane B took off at the same runway 5 minutes later. Both planes are flying at the same direction angle and the same path. At 10:10 a.m., the airport’s radar system detected plane A at (24, 18) and plane B at (8, 6). The scale on the radar is 1 unit = 25 miles.Which vector represents the path from plane A to plane B, and what is the actual distance between them?

A
components:, distance between planes: about 20 miles
Option A
B
components:, distance between planes: about 500 miles
Option B
C
components:, distance between planes: about 20 miles
Option C
D
components:, distance between planes: about 500 miles
Option D
5

Let w = where O(–5, 6) and R(4, –2). What is the component form of w?

Question illustration
A
LeftAngleBracket negative 0.2, 0.8 RightAngleBracket
Option A
B
LeftAngleBracket negative 5, 20 RightAngleBracket
Option B
C
LeftAngleBracket 1.8, negative 1.6 RightAngleBracket
Option C
D
LeftAngleBracket 45, negative 40 RightAngleBracket
Option D
6

Let q = ⟨15, –3⟩, r = ⟨–5, 8⟩, and s = ⟨10, –1⟩. What is r – q + 2s?

A
⟨0, 3⟩
B
⟨0, 9⟩
C
⟨40, 3⟩
D
⟨40, -13⟩
7

Let u = ⟨1, 5⟩, v = ⟨–3, 3⟩, and w = ⟨2, 3⟩. What is the direction angle of 4w – (2u + v)?

A
θ = 59.0°
B
θ = 173.7°
C
θ = 276.3°
D
θ = 353.7°
8

Review the diagram.

Question illustration
A
11.49 foot-pounds
B
38.30 foot-pounds
C
574.53 foot-pounds
D
750.00 foot-pounds
9

Review the graph.

Question illustration
A
LeftAngleBracket 7, negative 3 RightAngleBracket and 23 degrees
Option A
B
LeftAngleBracket negative 7, 3 RightAngleBracket and 23 degrees
Option B
C
LeftAngleBracket 7, negative 3 RightAngleBracket and 157 degrees
Option C
D
LeftAngleBracket negative 7, 3 RightAngleBracket and 15.7 degrees
Option D
10

Let a =⟨–7, 3⟩ and b =⟨–2, –12⟩, and c = a + b. What is the magnitude and direction angle of c?

A
|c| = 18; θ = 135°
B
|c| = 18; θ = 225°
C
|c| = ; θ = 135°
Option C
D
|c| = ; θ = 225°
Option D
11

Given vectors u = ⟨–2, 1⟩ and v = ⟨4, –2⟩, which statement is true concerning u and v?

A
The vectors form an obtuse angle of approximately 93°.
B
The vectors form an obtuse angle of approximately 96°.
C
The vectors form an obtuse angle of approximately 127°.
D
The vectors point in opposite directions.
12

Two planes take off from the same airport at approximately the same time. Plane A has an airspeed of 600 mph and travels in the direction S 20° W. Plane B has an airspeed of 450 mph and travels in the direction N 35° E.Which diagram represents the distance, x, between the planes?

A
On a coordinate plane, a vector labeled 450 miles per hour goes up and to the left in quadrant 2 and forms angle a = 35 degrees with the y-axis. A vector labeled 600 miles per hour goes down and to the left in quadrant 3 and forms angle beta = 20 degrees with the y-axis. Vector x goes from terminal point 600 miles per hour to terminal point 450 miles per hour.
Option A
B
On a coordinate plane, a vector labeled 450 miles per hour goes up and to the right in quadrant 1 and forms angle a = 35 degrees with the y-axis. A vector labeled 600 miles per hour goes down and to the left in quadrant 3 and forms angle beta = 20 degrees with the y-axis. Vector x goes from terminal point 600 miles per hour to terminal point 450 miles per hour.
Option B
C
On a coordinate plane, a vector labeled 450 miles per hour goes up and to the left in quadrant 2 and forms angle a = 35 degrees with the y-axis. A vector labeled 600 miles per hour goes down and to the right in quadrant 4 and forms angle beta = 20 degrees with the y-axis. Vector x goes from terminal point 600 miles per hour to terminal point 450 miles per hour.
Option C
D
On a coordinate plane, a vector labeled 450 miles per hour goes up and to the right in quadrant 1 and forms angle a = 35 degrees with the y-axis. A vector labeled 600 miles per hour goes down and to the right in quadrant 4 and forms angle beta = 20 degrees with the y-axis. Vector x goes from terminal point 600 miles per hour to terminal point 450 miles per hour.
Option D
13

A vector in standard position has its terminal point at (7, –4). What is the magnitude of the vector?

A
StartRoot 3 EndRoot
Option A
B
3
C
StartRoot 65 EndRoot
Option C
D
65
14

A plane flies 35 km in the direction N 30° W, then flies 60 km in the direction N 60° E. How far is the plane from its original location?

A
29.64 km
B
58.21 km
C
69.46 km
D
93.66 km
15

Review the graph.

Question illustration
A
N 60° E
B
N 60° W
C
S 60° E
D
S 60° W

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