Can I get help with a car speed question? (to fight a traffic ticket)

[LaureeF]

Can anyone tell me how much the speed of a car going 60 mph would slow down going up a 30 degrees incline?

 

[smileandbehappy]

It depends on how much force was driving the car doesn't it... :)

Do you mean how much the car could decelerate? If you take gravity and use some right angled triangles you can work that out simply enough. If you mean other things then you don't have enough information. How much a car would slow down to me could be deceleration or final velocity after some distance.

 

[billy_joule]

Having driven up the worlds steepest street myself (19 degrees)
http://en.wikipedia.org/wiki/Baldwin_Street

I can safely say that transitioning to a 30 deg slope at 60 mph would be quite violent and likely result in damage to both yourself and your car, you may want to borrow a friends car and hire a stunt man, good luck

 

[davenn]

Having driven up the worlds steepest street myself (19 degrees)
http://en.wikipedia.org/wiki/Baldwin_Street

yup it's a steep one
That's my ol' home townand to the OP ... yes, agreed, way too little information so far from you

 

[LaureeF]

It depends on how much force was driving the car doesn't it... :)

Do you mean how much the car could decelerate? If you take gravity and use some right angled triangles you can work that out simply enough. If you mean other things then you don't have enough information. How much a car would slow down to me could be deceleration or final velocity after some distance.

Thank you for responding. The truth is I need the information to fight a traffic ticket. The car was completely stopped. Then with normal acceleration it traveled 200 yards up a 30 degree incline. At the 200 yard mark a policeman said I was doing 67 mph. Aside from absolutely knowing that the top speed I reached was 53 mph, I am trying to prove that my car could not have reached 67 mph starting from zero in 200 yards going uphill at a 30 degree angle. It's not like it is a sports car. It's a Toyota Matrix - not exactly a speedy car. And I'm 68 years old. I'm almost never in a hurry anymore. Lauree

 

[Vanadium 50]

I think you need to remeasure some things - in particular the 30 degree angle. 200 yards at 30 degrees means you would be thirty stories up at the end.

 

[OCR]

The truth is I need the information to fight a traffic ticket.

Well, the best of luck in your fight... and you probably weren't, but ... Lol... only here ... and only him...

 

[LaureeF]

Having driven up the worlds steepest street myself (19 degrees)
http://en.wikipedia.org/wiki/Baldwin_Street

I can safely say that transitioning to a 30 deg slope at 60 mph would be quite violent and likely result in damage to both yourself and your car, you may want to borrow a friends car and hire a stunt man, good luck

You're right! It's only 3 degress, not 30 degrees. Little mistake (lol). Thanks.

 

[Vanadium 50]

I still think you need to remeasure things. 0-53 in 200 feet implies a 0-60 time of 5.8 seconds. While there are vehicles that can do that, the Toyota Matrix is not one of them.

 

[cjl]

I still think you need to remeasure things. 0-53 in 200 feet implies a 0-60 time of 5.8 seconds. While there are vehicles that can do that, the Toyota Matrix is not one of them.

To be fair, the quoted distance was 200 yards, not feet. Taking the police officer's figure, 0-68mph in 200 yards is 0-60 in 10.9 seconds (and 0-68 in 12.2 seconds), which is an easily attainable figure in a large proportion of modern cars (though it would actually need to be faster than this, since I assumed linear acceleration).

Adding the slope into account, a quick and dirty calculation I just ran indicates that the hill would soak up about 15 horsepower or so on average during such an acceleration run. Honestly, these numbers are making it look like it would be possible for a lot of cars to achieve this performance, though it would involve accelerating fairly briskly (possibly pretty close to floored, for a lot of normal commuter cars).

 

[LaureeF]

I still think you need to remeasure things. 0-53 in 200 feet implies a 0-60 time of 5.8 seconds. While there are vehicles that can do that, the Toyota Matrix is not one of them.

It's 200 yards, not feet.

 

[Vanadium 50]

Even that is pushing it. That would require your foot to be on the floor for the whole time.

 

[LaureeF]

To be fair, the quoted distance was 200 yards, not feet. Taking the police officer's figure, 0-68mph in 200 yards is 0-60 in 10.9 seconds (and 0-68 in 12.2 seconds), which is an easily attainable figure in a large proportion of modern cars (though it would actually need to be faster than this, since I assumed linear acceleration).

Adding the slope into account, a quick and dirty calculation I just ran indicates that the hill would soak up about 15 horsepower or so on average during such an acceleration run. Honestly, these numbers are making it look like it would be possible for a lot of cars to achieve this performance, though it would involve accelerating fairly briskly (possibly pretty close to floored, for a lot of normal commuter cars).

Thank you. You've been a big help. I appreciate it.

 

[Vanadium 50]

I did goof with feet, but even with yards, it involves flooring it. Apologies for switching to metric: 53mph means 280 J/kg from kinetic energy. A 3 degree hill means a rise of 9.6 m, or 95 J/kg from potential energy (a 33% "tax", if you will). That means, on an equivalent flat surface, the car would go sqrt(4/3) faster, or 61 mph at the end of the 200 yards. That's a 0-60 time of 13.1 seconds.

Edmunds says 11 seconds. While this is possible, it requires a foot pretty much on the floor. That's inconsistent with the "normal acceleration" description. Which is why I think remeasuring is in order.

 

[LaureeF]

I did goof with feet, but even with yards, it involves flooring it. Apologies for switching to metric: 53mph means 280 J/kg from kinetic energy. A 3 degree hill means a rise of 9.6 m, or 95 J/kg from potential energy (a 33% "tax", if you will). That means, on an equivalent flat surface, the car would go sqrt(4/3) faster, or 61 mph at the end of the 200 yards. That's a 0-60 time of 13.1 seconds.

Edmunds says 11 seconds. While this is possible, it requires a foot pretty much on the floor. That's inconsistent with the "normal acceleration" description. Which is why I think remeasuring is in order.

 

[LaureeF]

Thank you for taking the time to help me. It is truly appreciated.

 

[LaureeF]

I did goof with feet, but even with yards, it involves flooring it. Apologies for switching to metric: 53mph means 280 J/kg from kinetic energy. A 3 degree hill means a rise of 9.6 m, or 95 J/kg from potential energy (a 33% "tax", if you will). That means, on an equivalent flat surface, the car would go sqrt(4/3) faster, or 61 mph at the end of the 200 yards. That's a 0-60 time of 13.1 seconds.

Edmunds says 11 seconds. While this is possible, it requires a foot pretty much on the floor. That's inconsistent with the "normal acceleration" description. Which is why I think remeasuring is in order.

Thank you so much for your help. It was very kind of you.

 

[Vanadium 50]

Now that I think about it, I think you have given us enough information to refute your position. (Sorry, but that's how it works out). You want to show that with normal acceleration, you got to 53 mph, but that the car mechanically could not reach 68 mph in the same stretch. Is that right?

The key is "normal acceleration". My car can provide 200hp, but under normal acceleration, it's 100 hp or even less. If you can reach 53 with normal acceleration, you can probably reach 68 by flooring it.

 

[cjl]

Now that I think about it, I think you have given us enough information to refute your position. (Sorry, but that's how it works out). You want to show that with normal acceleration, you got to 53 mph, but that the car mechanically could not reach 68 mph in the same stretch. Is that right?

The key is "normal acceleration". My car can provide 200hp, but under normal acceleration, it's 100 hp or even less. If you can reach 53 with normal acceleration, you can probably reach 68 by flooring it.

Yes, and unfortunately, if the car is physically capable of reaching 68mph in that distance, you can't refute the officer's claim, unless you have a way to conclusively prove that you weren't flooring the accelerator.

 

[CWatters]

Was your sat nav on?

 

[stevmg]

If free wheeling and no friction, would decelerate at 16 ft/sec^2.
Time to decelerate totally = 88 ft/sec/(16 ft/sec^2) = 5.5 sec
Distance = 8 x 5.5^2 = 152.25 ft

A pretty rapid slowdown

 

[cjl]

If free wheeling and no friction, would decelerate at 16 ft/sec^2.
Time to decelerate totally = 88 ft/sec/(16 ft/sec^2) = 5.5 sec
Distance = 8 x 5.5^2 = 152.25 ft

A pretty rapid slowdown

That's half a gee of acceleration, which seems very wrong. How did you calculate this value?

 

[Carno Raar]

I doubt flooring the gas would be required.

I did some Googling as they don't sell the Matrix where I am, so I'd never heard of it. It's a hot hatch / sports subcompact. The smallest engine model I can find is a 1.8L with 10 seconds for 0-60 mph. The other version has a 2.4L.

 

[cjl]

I doubt flooring the gas would be required.

I did some Googling as they don't sell the Matrix where I am, so I'd never heard of it. It's a hot hatch / sports subcompact.

I generally wouldn't call something a "hot hatch" or "sports subcompact" unless it's actually sporty. The matrix is definitely a small hatchback, but with 158 horsepower in the most powerful trim, and either 205 or 215 wide tires (depending on trim), I'd hardly consider it sporty. In addition, a small incline can make a large difference in the acceleration of a low-horsepower car, so even with the larger motor, I'd expect ~10 seconds 0-60 to be pretty much flooring the accelerator given the hill.

 

[Carno Raar]

I don't see how you can't consider it sporty. For its age and size it has a very large engine (1.8L - 2.4L). What did a Ford Focus have in 2003? 1.6L to 2.0L on a larger car.

 

[cjl]

I don't see how you can't consider it sporty. For its age and size it has a very large engine (1.8L - 2.4L). What did a Ford Focus have in 2003? 1.6L to 2.0L on a larger car.

In the US, 2L or so is quite small on pretty much any class of car, and 130-150hp is low to average. Neither its power nor its engine size is particularly remarkable here. Also, I wouldn't consider a Focus to be a larger car - the curb weight of a Focus from the same time frame was actually slightly lower than the curb weight of the Matrix, and the Focus has just as much horsepower. In addition, the Focus isn't a hot hatch either, unless you look at the RS or ST versions.