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PHY 101 PHY 101 Past Questions Objective Question
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Question

Find the scalar product and the angle between the two vectors A = 2i + 3j + k and B = -4i + 2j - k.
Options
A -3, 100.1°
Correct Answer
B 3, 100.1°
C 4, 200.1°
D -4, 200.1°
Correct Answer

Option A is the correct answer.

Detailed Explanation

A·B = (2)(-4) + (3)(2) + (1)(-1) = -8 + 6 - 1 = -3. |A| = √(4+9+1) = √14 ≈ 3.742. |B| = √(16+4+1) = √21 ≈ 4.583. cos θ = -3/(3.742×4.583) = -3/17.15 = -0.175. θ = cos⁻¹(-0.175) = 100.1°.

Hint

A·B = |A||B|cos θ.

Question Info

Course: PHY 101
Topic: PHY 101 Past Questions
Type: Objective
Difficulty: Not specified
Question 1041 of 1250
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