Why, in terms of Physics so forces etc... does the diameter of a the splash from a raindrop increase when the height is also increased?
Drakkith said:Because the velocity of the drop increases as the height increases until it reaches terminal velocity. When it impacts a surface the kinetic energy is transferred into the splash.
koat said:Thanks but I don't really understand it.
Can you tell me why v increases when the height increases?
And also can you explain what terminal velocity has to do with this problem?
Ok I understand it so far but why does the diameter increse?Drakkith said:Gravity on Earth causes everything to accelerate at approximately 9.8 m/s^2. So the higher the object is when it starts falling, the longer it falls and the faster it gets. If a drop falls for 2 seconds its current velocity is less than an identical drop that has fallen for 4 seconds.
Terminal velocity causes there to be a maximum velocity something can reach while falling due to drag, or air resistance on the object. A rock has a much higher terminal velocity than a feather because the mass, size, and shape of the rock causes it to experience less drag.
Take a sheet of paper and just drop it from arms length. As it falls you will notice that it falls very slowly when the paper is horizontal. As it falls the paper will generally twist and turn so that it is no longer horizontal. When it starts to become more vertical it will fall much faster than before. Now, take that same sheet of paper and crumple it up into a ball and drop it. It has much less surface area than it did as a sheet and therefore experiences less drag.
It applies to your question because a water drop can only reach a certain speed before the resistance due to drag equals out the acceleration from gravity and the droplet more or less stops accelerating. Because air is less dense at higher altitudes a water drop from a cloud will accelerate, reach terminal velocity, and then start to slow down as the air becomes thicker and drag starts to increase.
koat said:Ok I understand it so far but why does the diameter increse?
Drakkith said:When you increase the velocity of the drop it acquires more kinetic energy. This energy has to go somewhere. When the drop hits, a faster drop has more energy to transfer into the splash than a slower drop does.
Go outside and find a rock or a baseball or something. Take it and drop it into some dirt. Notice that some of the dirt has been thrown away from the impact point, similar to the splash of a water drop. Now take that same object and THROW it into the dirt. Now much more dirt has been thrown out and to a longer distance. The extra energy provided by you had to go somewhere, and that somewhere was into the dirt.
koat said:But didn't you say that the drop slows down?
Why does the v increse now?
Do you mean that there is no terminal v at all?Drakkith said:The water drop only slows down if it falls from a high enough altitude, like from a rain cloud, to reach terminal velocity at that altitude and then keep falling through denser air. At ground level and at the scale of us people nothing has enough time to reach terminal velocity, so unless you get on a really tall building or tower then everything you drop will continue to accelerate until it hits the ground.
koat said:Do you mean that there is no terminal v at all?
Drakkith said:Terminal velocity changes with the altitude. Or more correctly, it changes with the density of the medium, in this case the air in the atmosphere. Since air is denser at lower altitudes the amount of drag increases as you get lower, causing the terminal velocity of an object to gradually decrease as an it falls.
koat said:I know what terminal v is I am just confused because here you say that the terminal v decreases but in the previous post you said it's just normally accelerating downwards.
Sorry but can you maybe explain that again?
The relationship between raindrop splash diameter and height is a direct one. As the height from which the raindrop falls increases, the diameter of the splash also increases due to the increasing force of impact.
The size of the raindrop has a direct effect on the splash diameter. Larger raindrops have a greater surface area and therefore create a larger splash upon impact. However, the height from which the raindrop falls also plays a role in determining the splash diameter.
Yes, there is a specific height at which the raindrop splash diameter is maximized. This height is typically around 6 inches, but can vary depending on the size and velocity of the raindrop.
The surface tension of the water plays a significant role in determining the raindrop splash diameter. Higher surface tension results in a more compact splash, while lower surface tension results in a more spread out splash.
Yes, there are several other factors that can affect the raindrop splash diameter, such as wind speed, air pressure, and the surface properties of the impact surface. These factors can alter the shape and size of the splash, making it difficult to predict the exact diameter for a given raindrop.