Super Fast Zipcars
My wife tweeted a post to @zipcarChicago about a recent bill. In a nutshell we were charged for 3,003 miles today for renting the commuter vehicle. https://twitter.com/queensuchnsuch/status/1056013294492938246?s=21
So being me... I thought “Oh maths!” Let’s see, the Honda CRV AWD has a curb weight of 3,421 lbs, and a 4 cylinder, 184 horsepower motor. When you weigh it, you don't actually get the mass, but the weight, which is the mass multiplied by the acceleration due to gravity, which is 32/feet/second2. If you measure the weight in pounds, divide that number by 32 feet/second2 to get the mass in units called slugs. The CRV is about 107 slugs.
Now it's time to do an acceleration test to find how long it takes the car to reach a speed of 60 miles per hour from a standstill. Convert that final speed to feet/second and divide it by the time it took to attain that speed. That gives you the average acceleration. Now you have all you need to find the thrust developed by the engine because, according to Newton's Second Law, Force (Thrust) = Mass • Acceleration. The CRV does 0-60 in 7.5 seconds. Dividing the maximum speed in feet per second by 7.5 seconds, we get an average acceleration of 11.7 feet/second2. That means the engine develops (107 slugs • 11.7 ft/s2) = 1,251 pounds of thrust at full throttle.
You know the horsepower rating of the engine, and now you know the thrust, so you can calculate the speed the car will travel using the relationship: Speed = Power/Force. To arrive at an answer, we note that that 1 Horsepower = 550 ft.-lb./s, and the engine develops 184 HP, which is 101,200 ft.-lb./s. We divide that by the thrust calculated in the acceleration test. Accordingly, the Honda CRV a should be able to travel at a speed of 80.9 feet/second, or a little over 55 miles per hour while developing that amount of thrust.
A Honda CRV actually can travel faster than 55 miles per hour. It won't develop its top speed while developing that amount of thrust, though. Speed and force are in an inverse relationship, so reducing the acceleration, which reduces the force the engine needs to exert, increases the speed. If you own a Honda CRV, and you want to see it travel 1.7 times the speed of sound, it first needs to be rented from Zipcar and then driven around the city of Chicago.
Thanks to sciencing for the math help. https://sciencing.com/convert-horsepower-miles-per-hour-2802.html
So being me... I thought “Oh maths!” Let’s see, the Honda CRV AWD has a curb weight of 3,421 lbs, and a 4 cylinder, 184 horsepower motor. When you weigh it, you don't actually get the mass, but the weight, which is the mass multiplied by the acceleration due to gravity, which is 32/feet/second2. If you measure the weight in pounds, divide that number by 32 feet/second2 to get the mass in units called slugs. The CRV is about 107 slugs.
Now it's time to do an acceleration test to find how long it takes the car to reach a speed of 60 miles per hour from a standstill. Convert that final speed to feet/second and divide it by the time it took to attain that speed. That gives you the average acceleration. Now you have all you need to find the thrust developed by the engine because, according to Newton's Second Law, Force (Thrust) = Mass • Acceleration. The CRV does 0-60 in 7.5 seconds. Dividing the maximum speed in feet per second by 7.5 seconds, we get an average acceleration of 11.7 feet/second2. That means the engine develops (107 slugs • 11.7 ft/s2) = 1,251 pounds of thrust at full throttle.
You know the horsepower rating of the engine, and now you know the thrust, so you can calculate the speed the car will travel using the relationship: Speed = Power/Force. To arrive at an answer, we note that that 1 Horsepower = 550 ft.-lb./s, and the engine develops 184 HP, which is 101,200 ft.-lb./s. We divide that by the thrust calculated in the acceleration test. Accordingly, the Honda CRV a should be able to travel at a speed of 80.9 feet/second, or a little over 55 miles per hour while developing that amount of thrust.
A Honda CRV actually can travel faster than 55 miles per hour. It won't develop its top speed while developing that amount of thrust, though. Speed and force are in an inverse relationship, so reducing the acceleration, which reduces the force the engine needs to exert, increases the speed. If you own a Honda CRV, and you want to see it travel 1.7 times the speed of sound, it first needs to be rented from Zipcar and then driven around the city of Chicago.
Thanks to sciencing for the math help. https://sciencing.com/convert-horsepower-miles-per-hour-2802.html
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