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| Thread ID: 57767 | 2005-05-12 06:22:00 | Badly need help on my Algebra test | Renmoo (66) | PC World Chat |
| Post ID | Timestamp | Content | User |
| 354361 | 2005-05-12 11:35:00 | I sort of understand that terminal velocity is achieved when all forces are equal. As such, when she opens up her parachute, this will add extra drag to her speed, which results in inequal forces applying to her. Thus terminal velocity of Tara is "stopped". Someone point out my mistake, please. Cheers :) |
Renmoo (66) |
| 354362 | 2005-05-12 11:40:00 | I just did James! Terminal velocity is not determined by the parachute. This much is already clearly identified in the question. Google it, you will find out the error in your thinking. Cheers Billy 8-{) |
Billy T (70) |
| 354363 | 2005-05-12 12:02:00 | OK James. Terminal velocity (50m/s in this question - it's given to you!) is reached when the friction of the air is enough that it will not allow you to accelerate any further. Much the same way as once a car gets to its top speed (by engine power), no matter how it is geared it can not accelerate further. It won't continue to accelerate at 10KM/h per second or so forever. If a car will do 0-100Km/h in 10 seconds, it won't do 0-500Km/h in 50 seconds. Likewise, gravities acceleration of 9.8m/s^2 is purely in a vacuum. The air is working against this, trying to slow you down. Here's an example. Say the parachuter weighed 80kg. That equates to about 800N gravitational force pulling him towards the ground. Because drag force increases as speed increases, at a certain speed, the air will also be pushing 800N of drag in the other direction, so there will no longer be any acceleration. That speed is the terminal velocity. If that speed was say 100m/s, then the parachuter would reach that speed due to gravity, and then continue to fall at that speed without accelerating. It only takes a few seconds to reach this speed, or in the case of this question, 2.8 seconds. If you don't understand still, never fear - I am at this very moment drawing you a diagram based on distance. |
george12 (7) |
| 354364 | 2005-05-12 12:13:00 | www.jgi.co.nz/algebra.jpg | george12 (7) |