Question

A circus acrobat is shot out of a cannon with an initial upward speed of 34 ft/s. if the acrobat leaves the cannon 4 ft above the ground, how long will it take him to reach a net that is 8 ft above the ground

Answer 1

It will take 0.125 seconds to reach the net.

Explanation:

Initial speed, u = 34 ft/s = 10.36 m/s

Acceleration, a = -9.81 m/s²

Displacement, s = Final height - Initial height = 8 - 4 = 4 ft = 1.22 m

We have equation of motion, s = ut + 0.5 at²

Substituting

              s = ut + 0.5 at²

              1.22 = 10.36 x t + 0.5 x -9.81 x t²

              4.905t² - 10.36 t + 1.22 = 0

              t = 1.99 s     or    t = 0.125 seconds

Minimum time is 0.125 seconds.

It will take 0.125 seconds to reach the net.