Final answer:
The velocity of the ball after 1.5 seconds is 9.7 m/s downwards, calculated using the kinematic equation for velocity with the effects of gravity considered.
Step-by-step explanation:
To determine the velocity of the ball after 1.5 seconds when it is thrown with an initial upward velocity of 5 m/s, we use the kinematic equation: vf = vi + at, where vf is the final velocity, vi is the initial velocity, a is the acceleration, and t is the time. Since the ball is thrown upwards, gravity will act downwards as a negative acceleration (in this context, -9.8 m/s²).
Let's compute the velocity after 1.5 seconds:
vi = 5 m/s (upwards)
a = -9.8 m/s² (downwards)
t = 1.5 s
Substituting the values: vf = 5 m/s + (-9.8 m/s² * 1.5 s) = 5 m/s - 14.7 m/s = -9.7 m/s.
The negative sign indicates the direction of velocity is downwards. Therefore, after 1.5 seconds, the velocity of the ball is 9.7 m/s in the downward direction.