Heeeellllppppp!!!!! 10 POINTS:)?

Question

what is the formula for hang time? i mean if a person jumps high how can i figure out the time he's in the air?? i know the distance formula but how do u figure out from that distance formula???



thank you soo much!!

Answer 1

F=ma

The only force acting on a person after they have jumped (assuming no air resistance, which would factor in but is really complicated for an arbitrarily shaped object like a person) would be the force of gravity, so:

ma = -mg
a = -g

acceleration is the second time derivitive of position, so:

dy^2/dt^2 = -g

Integrating with respect to time:

dy/dt = -gt + C1

This is the velocity, and the constant C1 is the velocity at t=0, which is the initial velocity of the jump, so:

v = -gt + v0

The integral with respect to time the velocity we get:

y = -1/2gt^2 +v0t + C2

C2 is the initial position, which is the ground, which we call 0, so:

y = -1/2gt^2 + v0t

assuming g=9.8m/s^2

y = -4.9t^2 + v0t

the person is on the ground at the times where y=0, so:

0 = -4.9t^2 + v0t

the roots of that equasion are first t=0 (the person when they start on the ground. the other is the useful one (the time they return to the ground) which is:

t = v0/4.9

So at the time found by dividing the initial velocity by 4.9, you get the time at which they touch the ground, which is the 'hang time'.

Answer 2

there is a way to do this with a formula but it would require so much information to use that you would better off just using a good stop watch, stat when he jumps, stop when he lands.

story guy is not right! if you could measure the exact maximum hieght of the jump, the distance formula woudl not work becase you need ot take into count acceleration.

it would be ((2*x)/g))^(1/2) where x is the hieght and g is the acceleration due to gravity. if you use g= 9.8 meters/s^2 the hieght x has to be in meters.

Answer 3

For that you would have to know the distance from ground 0 to ground Y (from the ground to the maximum value of the jump ((highest point))) and seeing as the distance formula is:

TV = D then you would need to know the velocity and the distance so then you would have T = D/V and that will be your formula.

Answer 4

height= (initial velocity)(time) + (1/2)(acceleration)(time^2)
Assuming you are starting from rest in the vertical direction, the initial velocity is zero.
acceleration is due to gravity, 9.8m/(sec^2)
so:
height=(1/2) (9.8m/sec^2)t^2
Solve for t
________________________

After coming back to this topic, I realized that I initially made the mistake of dismissing this as a simple free-fall problem when it involves parabolic projectile travel.

When calculating the time of parabolic projectile travel it is important to take into consideration the velocities and displacements along both the x-axis (horizontal) and the y-axis (vertical).

Horizontally your equations would be:
Δd = Voxt + ½axt²
Δd = distance traveled horizontally
Vox = initial velocity along the x-axis
t= time
Ax = acceleration along the x-axis
Neglecting air friction the acceleration would be zero, therefore:
Δd = Voxt

Vertically:
Δh = Voyt + ½Ayt²
Ay = acceleration along the y-axis = gravity
Voy = initial velocity along the y-axis
Δh = difference in height

It becomes apparent that in order to calculate the air-time correctly, one must either know:
Both Δd and Vox
Or
Both Voy and Δh

Solving for the air-time would be possible knowing only Voy, but I don’t think it is necessary to expound on that in this topic.

Answer 5

If you know how high the jump is, you can figure it out using s = gt^2 (solving for t), where g is the acceleration due to gravity in appropriate units.

Answer 6

A stop watch!
It's very simple and I'm voting for a previous answerer who told you that already.

Yours;
Jonnie

PS It's not a function of some obtuse complicated mathematical function or formula ... just time it. Duh. Math can't do it without knowing innumerable details like exactly how high the jump was Etc.

Some of these other answerers were just kidding you ... or they are truly insane, and I don't judge them. Goodnight.

Answer 7

take aerodynamic and know that the fast-es one can fall is written in free fall charts about 86 ft. per second.that should help out a little

Answer 8

you'd have to have a formula with vertical velocity and gravity. KE=PE

Answer 9

What storyguy13 said is 100 percent correct.

T = D/V

Answer 10

Hang time would have to be checked with a stop watch.