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Velocity vector
By Anonymous on Thursday, January 11, 2001 - 07:58 pm:

Hi,

I am not to sure how to the following of a part of a question. Can someone explain how and why it works?

With respect to a fixed origin O, the velocity v ms-1 of a particle P at time t seconds is given by:

v = t2i + (5 - 4t)j

a) Find the value of t when P is moving parallel to the vector i.

Parallel to i: not sure what to do, and why.

Thanks in advance for any help.

By Oliver Samson (P3202) on Thursday, January 11, 2001 - 09:18 pm:

If it is moving parallel to i, it is moving in a straight line parallel to the x-axis. This means that y is a constant. If y isn't changing then the co-efficient of j, which in these circumstances represents the rate of change of y must be 0. Therefore:

5-4t=0
t=5/4

By Anonymous on Friday, January 12, 2001 - 09:39 am:

Thank you Oliver!