Question

A luge run is straight for the first 10 m. If the velocity of the luger when he passes the start line is +25 m/s and his acceleration is constant at +9.5 m/s2, about how fast is he going when he hits the first turn? A. +14 m/s B. +26 m/s C. +29 m/s D. +225 m/s

Answer 1

Recall that

${v_f}^2-{v_i}^2=2a\Delta x$

where $v_i$ is the luger's initial velocity, $v_f$ his final velocity, $a$ his acceleration, and $\Delta x$ the distance he traverses. Then

${v_f}^2-\left(25\,\dfrac{\mathrm m}{\mathrm s}\right)^2=2\left(9.5\,\dfrac{\mathrm m}{\mathrm s^2}\right)(10\,\mathrm m)$

$\implies v_f\approx29\,\dfrac{\mathrm m}{\mathrm s}$

so the closest answer is C.