Can I write -5m/s to the right?

[abc612008]

My teacher told me it's wrong to write -5m/s to the right since the negative sign and "to the right" are contrary and therefore don't make sense. However, she said it's okay to write -5m/s because it implies "to the right".
(The correct answer she said is 5m/s to the left)
(Sorry for not using the template because it is irrelvent to specific problem)

 

[haruspex]

My teacher told me it's wrong to write -5m/s to the right since the negative sign and "to the right" are contrary and therefore don't make sense. However, she said it's okay to write -5m/s because it implies "to the right".
(The correct answer she said is 5m/s to the left)
(Sorry for not using the template because it is irrelvent to specific problem)

It depends.
If the answer is 5m/s to the left then it is clearest to write it that way. But if you are working in Cartesian coordinates you would write $\dot x=-5m/s$.
So I would say your answer is technically correct but might not be the clearest in the circumstances.
I wouldn't say that "to the right" and the minus sign are contrary; they combine to produce "to the left".

 

[CWatters]

However, she said it's okay to write -5m/s because it implies "to the right".

If you define right as positive then a velocity of -5m/s implies motion to the left. So either that's a typo or she is wrong?

Stating "-5m/s to the right" is confusing but not invald, its a bit like using a double negative in an English essay.

 

[haruspex]

she said it's okay to write -5m/s because it implies "to the right".

either that's a typo or she is wrong?

I guess she meant that if you just say -5m/s without specifying left or right then the default is right positive, so "-5m/s" implies 5m/s to the left.