37. The position of a particle moving in the xy-plane is given by \( x = t^2 + 2t \), \( y = 2t^2 - 6t \). What is the speed of the particle when \( t = 2 \)?






Answer is: option1

\( 2\sqrt{10} \)

Solution:

The velocity vector is given by

\[ \begin{cases} \frac{dx}{dt} = 2t + 2 \\ \frac{dy}{dt} = 4t - 6 \end{cases} \]

When \( t = 2 \), the velocity vector is \( \mathbf{v}(2) = \langle 6, 2 \rangle \).

The speed of the particle is the length of this vector, \[ |\mathbf{v}| = \sqrt{6^2 + 2^2} = 2\sqrt{10}. \]

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