Hola, basically I'm doing M1 and I kind of hate maths at the moment so bare with me if I ask any ridiculous really obvious questions.
I've got an old exam question from 2003 & our teacher gave us all the final answer for it but I'm confused as to how she got it.
5. A particle P moved with constant acceleration (2i-3j)m/s^-2. At time t seconds, it's velocity is v/m/s^-1. When t=0, v=-2i+7j.
a. Find the value of t when P is moving parallel to the vector i. (I've done this bit & got it correct. The answer is t= 2 and a third seconds.)
b. Find the speed of P when t=3. (this is the bit I'm ridiculously stuck on. I don't understand how to get to the answer, is there a formula or something I should know about that and I'm just being a bit dense?)
c. Find the angle between the vector j and the direction of motion of P when t=3. (Haven't yet tried this, but I suck at maths so all help would be appreciated.)
Thank you for your help in advance, even if you have to roll your eyes at my stupidity please help me