These free fall problems will show you how to solve a variety of word problems related to objects that are falling from a certain height.
Problem #1: What is the instantaneous speed of a book dropped from the twenty fifth floor after 2.5 second?
Solution : The formula that gets you the instantaneous speed is v = g × t. Let us use g = 10 m / s^{2}Problem #2: A ball is thrown straight up in the air. If it takes the ball
2 seconds to reach its maximum height, what is the initial velocity?
When in the air, the ball is under the influence of gravity.
On the way up, the speed of the ball will decrease by 10 m / s each second until it reaches a speed of 0 ( maximum height)
The initial speed must have been 20 m / s.
The value of g is just a measurement. In math anything upward the yaxis is positive. Since the acceleration is downward the yaxis, it should really be g instead of just g.
Whenever you are solving free fall problems, keep the aforementioned in mind.
Problem #3 :
How high is a building if it takes 5 seconds for a ball to hit the floor ?
Pretend the object was dropped from the rooftop and a man was holding the ball at a height of 1 meter before letting it go
g × t^{2}
2

=
10 × t^{2}
2

=
10
2
× t^{2}

So, we can just use the formula above to simplify the problem.
d = 5 × 5^{2}However, the object was dropped from a height of 1 meter.
This is the height the man was holding the ball.
Therefore, subtract 1 from 125 to get the height of the building
h = 125  1 = 124.
The building is 124 meters.
This is a very interesting free fall problem because it give us another very efficient way to measure the height of a building.
Problem #4: Your turn to solve a free fall problem!
The world's tallest building is Burj Dubai. Rounded to the neatest 10, the building is 830 meters high. How long will it take an object to hit the floor?
Solve this free fall problem yourself and submit a detailed solution and explanations using the form below. This is for you to solve. I will not solve it for you! Then, I will select a winner.
Share your solution here. Don't submit your own problem here. It will be ignored!
Back to free fall equations
Mar 16, 17 03:15 PM
Great lesson about the law of reflection. Crystal clear explanation
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