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I have the following question

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To find the acceleration I rearrange the formula F = ma to get a = F / m.

This gives a = 5 / 2.5 = 2.

However, the solutions say that the answer should be the following:

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However, I am not sure how this answer is achieved.

1 Answers 1

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It seems a bit weird to see it drawn this way, but I think what the drawing is intended to represent is that there are two forces, each of $5$ N, acting on the body. Each force is represented by its own arrow, and that's why there are two arrows.

The arrows appear to be parallel, so I think we're supposed to conclude that the two forces are in the same direction. Two forces of $5$ N each in the exact same direction, applied to the same body, gives a total force of how much on that body?

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    A total force of 10N (: I understand that but I do not understand where the 5.0cm came from ? Haha – 2017-01-17
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    I agree, the 5.0 cm seems to be wrong. This notation is extremely odd anyway. You would want to give acceleration it's own vector, not mix it with a vector for an entirely different quantity. – 2017-01-17
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    Is the red arrow 5 cm long on the page in the printed edition of the book? After all, we're apparently supposed to be using a ruler to figure out the answers, if the wording of the question is to be believed. – 2017-01-17