Final answer:
The vertical speed of an object that was thrown horizontally off a cliff with an initial velocity of 5 m/s after 3 seconds is 29.4 m/s, calculated using the formula v = gt where g is the acceleration due to gravity (9.8 m/s²).
Step-by-step explanation:
The subject question is regarding the vertical speed of an object thrown horizontally off a cliff. When the object is thrown with an initial velocity horizontally, only gravity acts on it vertically. Assuming the acceleration due to gravity (g) is 9.8 m/s² and ignoring air resistance, the vertical speed of the object after 3 seconds can be calculated using the formula v = gt, where v is the final vertical velocity, g is the acceleration due to gravity, and t is the time in seconds.
Using this formula, the vertical speed is: v = 9.8 m/s² × 3 s = 29.4 m/s. Hence, the vertical speed of the object just before it strikes the ground is 29.4 m/s.