
William W. answered 03/23/23
Experienced Tutor and Retired Engineer
The horizontal direction is "x" so the horizontal velocity is dx/dt = 6t + 1
The vertical direction is "y" so the vertical velocity is dy/dt = 10t
At t = 3, the value of the horizontal velocity is 6(3) + 1 = 19
At t = 3, the value of the vertical velocity is 10(3) = 30
The speed is the magnitude of the combined vector = √(192 + 302) = 35.51