Kinematics: compare the velocities

Question

The motion equations of two moving bodies are:

x₁=1+3t

x₂=t+2t²

Compare the velocities during a) the end of first five seconds; b) the end of last five seconds

The correct answer for a) should be: (v₁/v₂)=3/21

Answer 1

You just need to remember that the derivative of position = velocity. So v₁ = 3 and v₂ = 1 + 4t.

I am slightly confused by what the "end of the last five seconds" means, but part a, the end of the first five seconds is just asking for a comparison when t = 5. Thus, v₁ = 3 and v₂ = 1 + 4(5) = 21

Thus, v₁/v₂ = 3/21 = 1/7.