Question

The place kicker on a football team kicks a ball from ground level with an initial speed of 8.40 m/s at an angle of 21.0° above the horizontal. How long is the ball in the air, in seconds, before it lands on the ground again? You may neglect air resistance.

Answer 1

See below

Step-by-step explanation:

Vertical component of the kick-off velocity is 8.4 sin21° = 3.01 m/s

Find the time-point where vertical velocity = 0 the ball is in the air for twice this long ( as it still has to fall back down to the ground)

vf = vo + at

0 = 3.01 m/s - 9.81 t shows t = .307 twice this is .614 sec

( what a sorry kick !)