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The force will act on both objects. With two objects of the same mass, they would accelerate at the same rate but in opposite directions. Let's suppose Allie and Shannon each have a mass of 50kg, and they're ice skating, so let's neglect friction. If they start from a standstill and they push each other away such that Allie has a final velocity of 1 m/s North, Shannon would have a final velocity of 1m/s South.
If the same situation happened but with Mike (75kg) instead of Shannon, Mike would have a final velocity of 0.667m/s South. With Jean (150kg), she would have a final velocity of 0.333m/s South. If there was a 1500kg car (in neutral, neglecting friction and angular momentum) instead of the other skater, the car would have a final velocity of 0.033m/s South.
Finally, let's have Allie push against a wall that is firmly attached to the earth (6x10^24kg). The change in the earth's surface velocity would be 8.3x10^-24m/s. That is insignificant enough to be impossible to measure. Therefore, it is neglected.
It feels like PHYS 218 all over again...
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If America manages to eliminate obesity, we would save as much fuel as if every American were to stop driving for three days every year. To be slender like Tiffany Yep is to be a real hypermiler...
Allie Moore and I have a combined carbon footprint much smaller than that of one average American...
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