What force is exerted on the windscreen?

  • Thread starter looi76
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In summary, the force exerted on the windscreen by the raindrops can be calculated by using the equation F = mΔv/t, where m is the mass of each raindrop, Δv is the change in velocity, and t is the time it takes for the raindrops to hit the windscreen. This can be determined by calculating the total mass of raindrops hitting the windscreen per second and multiplying it by the change in velocity.
  • #1
looi76
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Homework Statement


A car is driving through a rainstorm. Each raindrop of mass [tex]0.00005kg[/tex] hits the windscreen with velocity of [tex]16 ms^{-1}[/tex]. If [tex]500[/tex] raindrops hit the glass and run down the windscreen each second without bouncing, what force is exerted on the windscreen?

Homework Equations



Force = Mass x Acceleration

Momentum = Mass x Velocity

Inelastic Collisions:
[tex]m_1u_1 + m_2u_2 = (m_1+m_2)v[/tex]

The Attempt at a Solution



[tex]m = 5.0 \times 10^{-5}kg \ , \ u = 16ms^{-1}[/tex]

don't know how to start, need help!
 
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  • #2
The equations you gave are correct; but also remember that F = change in momentum / change in time.
Make sure you keep track of your units, and a force needs to end up being kg*m/s^2.
 
  • #3
Can someone please explain. Still, I don't know how to start =(
 
  • #4
As lzkelley said, force is change in momentum / time and momentum is mass * velocity.
The rain drop is accelerated to the speed of the car by the windscreen and so pushes on the widnscreen with a force equal to the raindrops mass * change in velocity.

Assuming the drop is falling vertically, you have the change in velocity, you know the total mass of raindrops falling per second so you have the force.
 

1. What causes the force exerted on the windscreen?

The force exerted on the windscreen is primarily caused by the pressure difference between the outside and inside of the vehicle. This pressure difference is created by the wind as it flows over the car and creates an area of high pressure in front of the windscreen and low pressure behind it.

2. How does the shape of the windscreen affect the force exerted on it?

The shape of the windscreen plays a significant role in determining the force exerted on it. A more streamlined and curved windscreen can reduce the pressure difference and thus, the force exerted on it. On the other hand, a flat or angled windscreen can increase the force exerted on it.

3. Can the force on the windscreen be affected by the speed of the vehicle?

Yes, the force exerted on the windscreen is directly proportional to the speed of the vehicle. As the speed increases, so does the pressure difference and consequently, the force on the windscreen increases. This is why the force on the windscreen is more noticeable at high speeds.

4. Is the force on the windscreen affected by the direction of the wind?

Yes, the force on the windscreen can be affected by the direction of the wind. If the wind is blowing directly towards the windscreen, the force will be greater compared to if the wind is blowing at an angle. This is because a headwind creates a larger pressure difference compared to a crosswind.

5. How does the material of the windscreen affect the force exerted on it?

The material of the windscreen can affect the force exerted on it in several ways. A stronger and more rigid material can better withstand the force and reduce any potential damage. Additionally, a smoother material can reduce the pressure difference and thus, the force exerted on the windscreen.

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