Coefficient of friction and drunk driver

In summary, the coefficient of friction is a measurement of the amount of friction between two surfaces in contact and is typically represented by the symbol "μ". It is an important factor in determining the braking distance of a vehicle and can be affected by driving under the influence of alcohol, which impairs reaction time and judgment. The average coefficient of friction for a sober driver depends on various factors, but is typically around 0.7 on dry pavement. A higher coefficient of friction means better grip and control of the vehicle, while a lower coefficient of friction, as is the case with drunk driving, can make handling more difficult and unpredictable. Unfortunately, the coefficient of friction cannot be improved for a drunk driver and the only way to ensure a higher coefficient of
  • #1
smw1016
7
0

Homework Statement



A drunk driver in a 2400kg car plows into a 1200kg parked car with its brake set. Police measurements show that the two cars skid together a distance of 25m before stopping.

If the effective coefficient of friction is 0.70, how fast was the drunk going just before the collision?


Homework Equations



Mv^2 / 2 = (M+m)μg * S i used this equation

2400*v^2/2=(2400+1200)*.70*25m

and i got 7.246 for v

what did i do wrong?

]
 
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  • #2
It looks to me like when you subbed in your values for the equation, you forgot acceleration due to gravity.
 
  • #3


Your calculation and use of the equation seems correct. However, it is important to note that the coefficient of friction is affected by various factors such as the type of surface and the condition of the tires. Additionally, the equation you used assumes that the two cars are sliding without any rotation, which may not be the case in a real-life scenario. Therefore, your calculated speed may not be entirely accurate. It is also important to consider other factors such as the reaction time of the drunk driver and the impact force of the collision. It is always best to use multiple equations and factors to get a more accurate estimation of the speed in a real-life situation.
 

1. What is the coefficient of friction?

The coefficient of friction is a measurement of the amount of friction between two surfaces in contact. It is typically represented by the symbol "μ" and is a unitless quantity.

2. How is the coefficient of friction related to driving while under the influence of alcohol?

The coefficient of friction is an important factor in determining the braking distance of a vehicle. When a driver is under the influence of alcohol, their reaction time and judgment are impaired, leading to a decrease in the coefficient of friction between their tires and the road. This can result in longer braking distances and an increased risk of accidents.

3. What is the average coefficient of friction for a sober driver?

The average coefficient of friction for a sober driver depends on many factors, including the type of tires, road conditions, and vehicle weight. However, on dry pavement, the coefficient of friction is typically around 0.7.

4. How does the coefficient of friction affect the handling of a vehicle?

The coefficient of friction is closely related to the grip of a vehicle on the road. A higher coefficient of friction means better grip, allowing the driver to maintain control of the vehicle. When the coefficient of friction is lowered, as is the case with drunk driving, the handling of the vehicle can become unpredictable and more difficult to control.

5. Can the coefficient of friction be improved for a drunk driver?

No, the coefficient of friction is a property of the surfaces in contact and cannot be improved for a drunk driver. The only way to improve the coefficient of friction is to ensure that the driver is sober and able to react quickly and make sound judgments while driving.

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