A hot air balloon is ascending at a rate of 7.5m/s when a passenger drops a camera. If the camera is 25m above the ground when it is dropped, how much time does it take for the camera to reach the ground, and what is the velocity just before it lands?

The time it takes for an object to reach a certain level given the distance and the initial velocity can be calculated through the equation,

d = V₀t + 0.5gt²

Where d is the distance, V₀ is the initial velocity, g is the acceleration due to gravity and t is time. Substituting the known values from the given above,

25 = (-7.5) (t) + 0.5 (9.8 m/s²) (t²)

The value of t from the equation 3.15s. Hence, it will take the object 3.15 seconds to reach the ground.