Ok, so two people are free falling. So they gain speed by the force of gravity. They reach approximately 40mph speed. If just before the fall the person on the bottom pushed the one on top can they generate enough power to slow down the person on top?
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No.
To slow down a person who is free falling, you need to have a net upward force--otherwise you just decrease the rate of acceleration. Force is mass times acceleration, and the gravitational acceleration is around 9.81 m/s^2 in most places. Say we have a person weighing 70 kilograms (just over 154 pounds), the force of gravity acting on their body is 70 * 9.81 = 686.7 N
Now, normally, some of this force will be countered by drag from the air. However, by definition, a free fall does not take into account drag. That means the person on the bottom needs to push with a force of 686.7 N to overcome the force of gravity. According to the link in my sources, the average human (among the test subjects) could push 138 pounds, or 613.854583 N in a horizontal direction.
This means that the average person couldn't counter the force of gravity acting on a 70 kilogram person. They would be able to lower the rate of acceleration, but not even start slowing down the other person.
People in the 95th percentile (95% of people are weaker) could push with a force of 934.126539 N, making a net force of 686.7 - 934.126539 = -247.426539 N, or a deceleration of 3.5346648428571428571428571428571 m/s^2. From a speed of 40 mph, or 17.8816 m/s, it would take you 17.8816 / 3.5346648428571428571428571428571 = 5.0589237721180750137720675145525 seconds to slow them down to a complete stop.
In other words, if you are among the 5% strongest people, it would take you about 5.1 seconds of sustained pushing to bring your average-weight friend to a standstill. The thing is, you're not pushing yourself to a standstill--you are pushing yourself away from your friend, with an equal force as you are pushing him away. So you simply can't push them long enough to slow them down significantly, and you don't have the force to slow them down significantly in one push.
To slow down a person who is free falling, you need to have a net upward force--otherwise you just decrease the rate of acceleration. Force is mass times acceleration, and the gravitational acceleration is around 9.81 m/s^2 in most places. Say we have a person weighing 70 kilograms (just over 154 pounds), the force of gravity acting on their body is 70 * 9.81 = 686.7 N
Now, normally, some of this force will be countered by drag from the air. However, by definition, a free fall does not take into account drag. That means the person on the bottom needs to push with a force of 686.7 N to overcome the force of gravity. According to the link in my sources, the average human (among the test subjects) could push 138 pounds, or 613.854583 N in a horizontal direction.
This means that the average person couldn't counter the force of gravity acting on a 70 kilogram person. They would be able to lower the rate of acceleration, but not even start slowing down the other person.
People in the 95th percentile (95% of people are weaker) could push with a force of 934.126539 N, making a net force of 686.7 - 934.126539 = -247.426539 N, or a deceleration of 3.5346648428571428571428571428571 m/s^2. From a speed of 40 mph, or 17.8816 m/s, it would take you 17.8816 / 3.5346648428571428571428571428571 = 5.0589237721180750137720675145525 seconds to slow them down to a complete stop.
In other words, if you are among the 5% strongest people, it would take you about 5.1 seconds of sustained pushing to bring your average-weight friend to a standstill. The thing is, you're not pushing yourself to a standstill--you are pushing yourself away from your friend, with an equal force as you are pushing him away. So you simply can't push them long enough to slow them down significantly, and you don't have the force to slow them down significantly in one push.