If the y component of the initial velocity for a projectile is ...

[Millan]

Need help on homework; I can't find the answer anywhere. Please help!

If the y component of the initial velocity for a projectile is 10m/s, how long will the projectile stay in the air before coming back to the original level?

A.) 10s
B.) 20s
C.) 2s
D.) 1s

Thank you!

[TI]

Answer C

When the projectile reaches the maximal height Vy = 0

Vy = V°y - gt  if Vy = 0 ---- V°y = g t and t = V°y /g = 10 / 9.8 = 1.02041 s

Y = V°y t - 1/2 g t^2 --- 10 * 1.02041 - 0.5 * 9.8 * 1.04123= 10.2041 - 5.10204 = 5.1020 m

The duration of the free fall is identical in the time of rise = 1.02041

Time total = 1.02041 * 2 = 2.0408 s

Goodbye