When does the speed equal 10 m/s?

[InsTanCeZ]

Homework Statement

The velocity v of a particle moving in the xy plane is given by v = (6.0t - 4.0t2) i + 6.0 j, with v in meters per second and t (> 0) is in seconds.

(d) When does the speed equal 10 m/s?

Homework Equations

?

The Attempt at a Solution

6-8t=-10
t=2s
That's not right

 

[Clever-Name]

Well, how is the speed defined in terms of the vector velocity