- D Use Big Five #5 with v 0 = 0 (calling down the positive direction).
- B First we determine the time required for the ball to reach the top of its
parabolic trajectory (which is the time required for the vertical velocity to
drop to zero).
The total flight time is equal to twice the following value:
- C After 4 seconds, the stone’s vertical speed has changed by ∆vy = ayt = (10
m/s^2 )(4 s) = 40 m/s. Since v 0 y = 0, the value of vy at t = 4 is 40 m/s. The
horizontal speed does not change. Therefore, when the rock hits the water, its
velocity has a horizontal component of 30 m/s and a vertical component of
40 m/s.
