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Vectors · Question 73 of 125

What is the work done by the force?

Question 73

MediumOriginal question

A constant force F⃗=2i^+2j^+k^\vec{F} = 2\hat{i} + 2\hat{j} + \hat{k} moves a particle from P(1,−1,2)P(1, -1, 2) to Q(3,2,1)Q(3, 2, 1). The work done is F⃗⋅PQ→\vec{F} \cdot \overrightarrow{PQ}.

What is the work done by the force?

Options for question 73

Show the answer and explanation
CorrectNot quiteAnswer B

Correct answer: B

Explanation

  1. F⃗⋅PQ→=2(2)+2(3)+1(−1)\vec{F} \cdot \overrightarrow{PQ} = 2(2) + 2(3) + 1(-1).

  2. 4+6−1=94 + 6 - 1 = 9.

Worth noting

−9-9 uses QP→\overrightarrow{QP}, the displacement in the wrong direction.

Concept
Computing a scalar product
Typical time
120 s
Your time
—
The rule this testsThe scalar product
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