Question

10. A skateboarder with a mass of 30 kg ends up with a final velocity of 7 m/s after a

Answer 1

Answer:

5 m/s

Explanation:

The net work is equal to change in kinetic energy hence

$360J= 0.5m(v_f^{2}-v_i^{2})$ where m is the mass of the skateboarder, v is the speed and the subscripts i and v represent initial and final respectively. Substituting 7 m/s for final velocity and 30 for mass m then

$360=0.5\times 30\times (7^{2}-v_i^{2})\\360=15(49-v_i^{2})\\\frac {360}{15}=49-v_1^{2}\\v_i^{2}=49-24\\v_i=\sqrt{25}\\v_i=5 m/s$