Physics Question: Car acceleration vs Airplane acceleration?
Friday, September 3rd, 2010 at
8:48 pm
Ok, I’ve always wondered this:
Why is it that when I’m in a sports car, and I slam on the gas from a stand still I get blasted back into my seat by the forward force, yet when I’m in an airplane, and as it accelerates down the runway, at a much faster acceleration rate and speed, I don’t get blasted back into my seat? I’m guessing it has to do with a pressurized cabin, or is it all in my head?
By plane I mean standard 747 passenger jet plane.
Great answers so far.
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The acceleration in your car is actually faster then in an airplane. (unless by airplane you mean an F-16) A 747 takes off at around 180 mph, and require most of a mile or more to get up to speed.
Where a fast car can go from 0-60 in only a few seconds, it take a plane longer, but the plane keeps accelerating at atleast this rate until it reaches takeoff speed.
the pressurized cabin has nothing to do with the laws of motion, your assumption that the plane is accelerating faster is inaccurate.
Who says the airplane acceleration is greater? The sports car may very well have a larger acceleration. Pressurization has nothing to do with the net forces acting on you, which is what you are feeling.
What planes are you talking about? Get in a jet on a air carrier ship and you will eat a lot more G then in a car. For commercial planes, they don’t do an acceleration race so that’s why you don’t feel anything, they slowly accelerate.
It all depends on the acceleration. If they wanted to, they could squeeze the gas like you do with your car with a Boeing 747 and trust me, you would not like it (neither the plane)
The truth is that you would feel the increasing acceleration of the airplane while rolling at the runway to reach its v rotation as it is called in aviation. V rotation is the speed at which the captain decides to pull back his control wheel or joystick to tilt the elevator upwards and thus creating an aircraft nose up when the aircraft has reached sufficient velocity to lift off. The only reason you won’t feel that pull back towards your seat is because the acceleration of the aircraft to reach VR is done in a much longer period. When you accelerate your car to reach 100 kilometer an hour, you could do it in less than 8 seconds for some sport cars; not so with an aircraft which usually rolls over one minute at the runway before lift off, which normally can be reached between 120 to 180 miles/hour. Some pilots are sometimes forced to hold their feet on the brakes while opening full throttle until the aircraft has reached a greater forward thrust starting from zero velocity to roll down the runway in a much shorter distance for lift off. Usually, in these cases, when the captain removes his feet from the brakes, the aircraft acceleration is felt strongly so that you could feel that force against the back of your seat much more than the normal way. This is usually done only when pilots take off from shorter runways at some airports.