- #1

PhysTeacher88

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For vf^2=vi^2 + 2ad, the opt not to use vectors.

Is there a deep reason why we would not want to use the vectors?

I understand that when you square the velocity, the direction information is lost, however, without making the acceleration and the displacement vectors (textbook reads distance because it's not a vector), students will not get questions like this correct:

A ball is thrown up at 10m/s, how high will it go?

If I treat everything as scalar, we get:

(0m/s) = (10m/s)^2 + (9.8)d

the distance ends up being a negative value, which is clearly not true given the context.

If they at least made the "a" and delta "d" vectors, they would not run into this problem.

I'm guess they took this formula from conservation of energy, rather than thinking about this from a kinematics perspective.

Am I missing something, or is this an oversight?

Cheers,

K