Solve Free-Fall Problem: A Ball Dropped from Rest

[ny_batteri4536]

I've spent about an hour and a half on this question, working with different formulas and manipulating equations but I still can't figure it out. The question:

"A ball, dropped from rest, covers three-quarters of the distance to the ground in the last second of its fall. From what height was the ball dropped, and what was the total time of the fall?"

I would type here what I have figured out, but really it seems like I have gotten nowhere. I think I've come close, though.

 

[Tide]

Why don't you tell us what your thinking is on the problem and give some indication of what you have tried.

 

[Andrew Mason]

I've spent about an hour and a half on this question, working with different formulas and manipulating equations but I still can't figure it out. The question:

"A ball, dropped from rest, covers three-quarters of the distance to the ground in the last second of its fall. From what height was the ball dropped, and what was the total time of the fall?"

I would type here what I have figured out, but really it seems like I have gotten nowhere. I think I've come close, though.

Work out the expression for total height in terms of total time.

Then work out how much distance is fallen in t-1. That will give you another expression for h. Can you take it from there?

AM

 

[Wishbone]

Convert what you said into an equatiom, think about distance=rate*time, and you will need to use that from free-fall the velocity of the ball at any time t is v=at, where a=9.8 m/s^2.

 

[Hootenanny]

Convert what you said into an equatiom, think about distance=rate*time, and you will need to use that from free-fall the velocity of the ball at any time t is v=at, where a=9.8 m/s^2.

It is not nesscary to find the velocity at any point during the free fall. The problem can be solved with the application of a single kinematic equation.