Very simple gravity/time/distance travelled problem

[dkayuk]

Homework Statement

This isn't really homework, because I'm not at school anymore (aged 42!) but I will describe as best as I can.

A small object like a droplet of water is released from a height (point A), falling on the surface (Point B) with initial speed 0. Distance between A and B, I will call d and obviously there's gravity (g) and time it takes for the droplet to fall from A to B, I will call t1. I know the equation so that given d is known, and so is gravity, then I can calculate time (t1).

Suppose that between points A and B, there's a point X. By the time the droplet has reached X is already has a certain speed. How do I calculate the time (t2) that it takes for the droplet to travel from X to the surface (B)?

Homework Equations

t1=square_root((2 * d)/g)

The Attempt at a Solution

I know (or at least I think I know) that I can't use the same equation to calculate t2 because the droplet already has a certain speed.

Apologies, if I'm not explaining this very well. I've not done any physics for 25 years and the reason I need this is because I'm doing high speed photography with falling objects.

thx

DK

 

[StElsewhere]

If you know the distance AX, you can use the above equation to calculate the time for the droplet to reach point X, t[X]. As t[1] stays the same whether or not you add an extra reference point, simply substract t[X] from t[1] and you have your answer.

Hope this helps.

 

[kerimek]

I can provide a response to your question. In order to calculate the time (t2) it takes for the droplet to travel from X to the surface (B), we can use the equation for constant acceleration: v = u + at, where v is final velocity, u is initial velocity, a is acceleration, and t is time. In this case, we can assume that the acceleration is constant due to gravity.

First, we need to calculate the initial velocity (u) of the droplet at point X. This can be done using the equation for distance: s = ut + 1/2at^2, where s is distance, u is initial velocity, a is acceleration, and t is time. We know the distance (d) between points A and X, and we can assume that the initial velocity at point A is 0. Therefore, we can solve for u, which will give us the initial velocity at point X.

Once we have the initial velocity (u), we can use the equation v = u + at to solve for t2. We know that the final velocity (v) at point B is 0, so we can plug in the values for u, a (gravity), and v into the equation and solve for t2.

I hope this helps and good luck with your high speed photography!