Posted by **AMY** on Thursday, July 1, 2010 at 12:09am.

A certain freely failing object requires 1.70 s to travel the last 20.5 m before it hits the ground. From what height above the ground did it fall?

- Physics -
**drwls**, Thursday, July 1, 2010 at 3:15am
Let H be the initial height.

Let T be the time it takes to fall the full height H.

g/2 T^2 = 4.9 T^2 = H

(g/2)(T-1.7)^2 = 4.9(T-1.7)^2 = H - 20.5

Combine the equations to eliminate H, so you can solve for T. Then calculate H.

4.9T^2 = 4.9(T-1.7)^2 + 20.5

4.9T^2 = 4.9T^2 -16.66 T +14.161 +20.5

16.66T = 34.66

T = 2.08 s

H = 4.9 T^2 = 21.2 m

- Physics -
**Maddy**, Saturday, October 23, 2010 at 3:15pm
Find the height from which you would have to drop a ball so that it would have a speed of 6.4 m/s just before it hits the ground.

## Answer this Question

## Related Questions

- physics - A certain freely failing object requires 1.70 s to travel the last 39....
- physics - A certain freely falling object requires 1.25 s to travel the last 35....
- Physics - A certain freely falling object requires 1.50 seconds to travel the ...
- physical - Q: a freely falling object requires 1.50s to travel the last 30.0m ...
- physics - An object is dropped from a height H above the ground. This free-...
- physics - An object is dropped from a height H above the ground. This free-...
- Physics - It takes a freely falling object 1.80 s to travel the last 32.00 m ...
- maths - A body of mass 11kg falls freely from rest from a height of 15m above ...
- maths - A body of mass 11kg falls freely from rest from a height of 15m above ...
- physices - an object is falling freely from rest of height of 65m above the ...

More Related Questions