Physics
posted by charlie .
Hi
Would someone be able to confirm that the following equation wil give the fall time for an object falling under gravity ignoring air resistance:
T= sq root of 2h/g
where h is fall height and g is accel due to local value for gravity.
A derivation from a more usual equation would be great too.
Thankc

Acceleration  The acceleration of a body is defined as the change in its velocity during an interval of time divided by the duration of the time interval. If Vo is the initial velocity at the beginning of the period of time and Vf is the final velocity at the end of the period of time, the change in velocity is Vo  Vf. If the velocity change occurs over the period of time t, the acceleration of the body is given by a = (Vo  Vf)/t.
The relationships between initial velocity, final velocity, distance covered and time, in uniformlay accelerated motion are defined mathematically by the following three equations:
1From a = (Vo  Vf)/t, the final velocity of a body under constant acceleration is given by Vf = Vo + at.
2The second equation regarding accelerated motion defines the distance traveled by a body under uniform acceleration.The average velocity of a moving body during a time interval "t" is expressed by Vav = (Vo + Vf)/2. The distance traveled, "s", during this time interval "t" is the product of the average velocity and the duraion of the time interval or s = (Vo + Vf)t/2. Substituting Vf = Vo + at into this expression yields s = [Vo + (Vo + at)]t/2 or s = Vot + at^2/2.
3The third equation of uniformly accelerated motion is derived from the first two by eliminating the time interval "t". Multiplying the two expressions results in as = (Vf  Vo)/t x (Vo + Vf)t/2 or Vf^2 = Vo^2 + 2as.
In summary,
Vf = Vo + at
s = Vot + at^2/2
Vf^2 = Vo^2 + 2as
These same equations apply to rising and falling bodies with the exception that a is replaced by g, the acceleration due to gravity.
For rising bodys,
Vf = Vo  gt
s = Vot  gt^2/2
Vf^2 = Vo^2  2gs.
For falling bodys,
Vf = Vo + gt
s = Vot + gt^2/2
Vf^2 = Vo^2 + 2gs
From s = h = Vot + gt^2/2
Since Vo = 0, h = gt^2 or t = sqrt(2h/g) 
Thanks very much
Respond to this Question
Similar Questions

physics
A student is testing the kinematic equations for uniformly accelerated motion by measuring the time it takes for lightweight plastic balls to fall to the floor from a height of 3 m in the lab. The student predicts the time to fall … 
science
When you first release the contraption and the egg, the force of gravity is pulling on the egg as it going to the ground. Which the force of the air resistance is trying to push up on the egg. The net force of the falling egg is equal … 
algebra
We can determine the time it would take an object to fall (if there were no air resistance) by using the formula where d is the distance. A. How long does it take a quarter dropped from a 35 foot roof to reach the ground? 
Math
Please help!! We can determine the time it would take an object to fall (if there were no air resistance) by using the formula where d is the distance.t=1/4sq.root of d, d being the distance 1. We can determine the time it would take … 
physics
An object was dropped from the top a tall building. During the last two seconds of the fall in traveled 80m. A) Find the total time of the fall. Assume that the gravitational acceleration is a constant 10m/s and air resistance is negligible. … 
AP Physics B
An object of mass 3.2 kg is allowed to fall from rest under the force of gravity for 3.5 s. What is the change in its momentum? 
MATH
If you do not consider air resistance, gravity causes a falling object to descend a distance of (9.8)t2 where t is the time in seconds. If a 16 pound bowling ball is dropped from the tallest building in the world, how many meters does … 
Science
Which of the following explains why a parachute makes a person falling from a great height fall more slowly? 
calculus help check and help
if an object with mass m is dropped from rest, one model for its speed v after t seconds, taking air resistance into account is v= mg/c(1e^(ct/m)) where g is the acceleration due to gravity and c is a positive constant describing … 
Physics
Galileo’s law of falling bodies states that the rate of fall caused by gravity is the same for all objects, regardless of weight. This means that all objects have a freefalling acceleration of 9.8m/s2. However, a significant contradiction …