At time t=0 an object is moving with velocity vector v⃗ =ki⃗ −2j⃗ and acceleration vector a⃗ =4i⃗ +2j⃗ . For what value of k is it possible that the object could be in uniform circular motion about some point in the plane?
K=

Question

At time t=0 an object is moving with velocity vector v⃗ =ki⃗ −2j⃗  and acceleration vector a⃗ =4i⃗ +2j⃗ . For what value of k is it possible that the object could be in uniform circular motion about some point in the plane? 
K=

anonymous · Answer

You have boxes... what are they supposed to be?

anonymous · Answer

I don't understand your question. I have no idea where to start with this

anonymous · Answer

You're going to have circular motion whenever acceleration and velocity perpendicular.

anonymous · Answer

So basically $$
\vec{v}\cdot \vec{a}=0
$$

anonymous · Answer

This will give you an equation for $k$.  Solve for $k$.

anonymous · Answer

ah ok, so do I do the dot product?

anonymous · Answer

Yes.

anonymous · Answer

Ok, let me work this out and if it's ok, I'll check the answer with you. Is that ok?

anonymous · Answer

better be quick then.

anonymous · Answer

I got k=-1, but it wasn't correct

anonymous · Answer

nvm it's k=1

anonymous · Answer

thanks for your help explaining

anonymous · Answer

There you go.