Laura can jump a vertical distance of 0.85 m. What is the total time she is off the ground? With what velocity does she hit the ground?

0.42 s, - 4.1 m/s

Explanation:

The time it takes to reach 0.85 meters is the same as the time it takes to fall back to the ground.

y = y₀ + vt - ½ at²

0.85 m = 0 m + (0 m/s) t - ½ (-9.8 m/s²) t²

t = 0.42 s

It takes 0.42 seconds to reach the maximum height. So it takes another 0.42 seconds to land. Therefore, Laura is in the air for 0.84 seconds.

v² = v₀² + 2a (y - y₀)

v² = (0 m/s) ² + 2 (-9.8 m/s²) (0 m - 0.85 m)

v = - 4.1 m/s

Laura hits the ground at a velocity of - 4.1 m/s.