Raindrops Sliding Down Car Window: Speed?

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In summary, the conversation discusses the observation of raindrops sliding down a car window at a 45 degree angle on a rainy day. The question of whether the force of the wind on the raindrops can be used to calculate the speed of the car is raised, but it is concluded that this is not possible without knowing the force holding the drops to the window. Factors such as friction and the size/shape of raindrops are also mentioned as potential influences on wind drag, but not gravity.
  • #1
daniel_i_l
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I was in a car on a rainy day and saw that the drops on the window were sliding down the window at about 45 deg. , I guess that that means that the force of the wind on the raindrops is about equal to the gravitational force but is that enough to calculate the speed of the car?
 
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Unfortunately, no: you need to know the force holding the drops to the window.
 
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russ_watters said:
Unfortunately, no: you need to know the force holding the drops to the window.
Yes. That would affect friction. Friction alters wind drag but not gravity. Same with size/shape of raindrops. Will affect wind drag, but not gravity.
 

What is the speed of raindrops sliding down a car window?

The speed of raindrops sliding down a car window can vary depending on the angle of the window, the density of the rain, and the speed of the car. Generally, raindrops have a terminal velocity of about 9 meters per second, but this can change depending on external factors.

Do raindrops slide down a car window at the same speed as they fall from the sky?

No, raindrops slide down a car window at a slower speed than they fall from the sky. This is due to the resistance of the window and the force of gravity pulling the raindrops down.

What factors affect the speed of raindrops sliding down a car window?

The main factors that affect the speed of raindrops sliding down a car window are the angle of the window, the density of the rain, and the speed of the car. The steeper the angle of the window, the faster the raindrops will slide. A higher density of rain and a faster speed of the car will also result in faster raindrop speeds.

Can the speed of raindrops sliding down a car window be calculated?

Yes, the speed of raindrops sliding down a car window can be calculated using the formula for terminal velocity: Vt = √(2mg/ρACd), where m is the mass of the raindrop, g is the acceleration due to gravity, ρ is the density of air, A is the cross-sectional area of the raindrop, and Cd is the drag coefficient. However, this calculation can be complex and may not be accurate due to the changing external factors.

Is there a difference in the speed of raindrops sliding down a car window on different types of windows?

Yes, there can be a difference in the speed of raindrops sliding down a car window on different types of windows. For example, a window with a hydrophobic coating will cause raindrops to slide faster compared to a window without a coating. Additionally, the material and thickness of the window may also affect the speed of the raindrops.

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