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PHY 101 PHY 101 Past Questions Objective Question

Question

Vector A has magnitude 8 units in the direction of the positive x-axis, vector B has magnitude 6√3 units and lies in the x-y plane, making an angle 30° with the positive x-axis and 60° with the positive y-axis. Find the vector product A × B.
Options
A 24√3 k
Correct Answer
B 24/3 k
C 24 k
D 24
Correct Answer

Option A is the correct answer.

Detailed Explanation

A = 8i. B has magnitude 6√3. Its components: B_x = 6√3 cos30° = 6√3 * (√3/2) = 6*3/2 = 9. B_y = 6√3 cos60° = 6√3 * (1/2) = 3√3. B_z = 0. So B = 9i + 3√3 j. Then A × B = (8i) × (9i + 3√3 j) = 8i × 9i + 8i × 3√3 j = 0 + 24√3 (i×j) = 24√3 k.

Hint

Write vectors in component form and compute the cross product.

Question Info