A ball is thrown from a hot air balloon that is at rest 245 m above the ground. How long will it take for the ball to reach the ground? How fast will the ball be traveling when it reaches the ground?

7.07 s

69.3 m/s

Explanation:

Taking the negative direction to be down and the positive direction to be up:

We have 3 variables in the y-direction and can solve for time.

Use this kinematics equation to solve for time.

It will take the ball 7.07 s to reach the ground.

We can solve for final velocity using the same variables in the y-direction:

Use this kinematics equation to solve for final velocity.

The ball will be traveling at a speed of 69.3 m/s at the instant before it reaches the ground.

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.