A projectile fired upward from the Earth's surface will usually slow down, come momentarily to rest, and return to Earth. For a certain initial speed, however it will move upward forever, with its speed gradually decreasing to zero just as its distance from Earth approaches infinity. The initial speed for this case is called escape velocity. You can find the escape velocity v for the Earth or any other planet from which a projectile might be launched using conservation of energy. The projectile of mass m leaves the surface of the body of mass M and radius R with a kinetic energy Ki = mv²/2 and potential energy Ui = -GMm/R. When the projectile reaches infinity, it has zero potential energy and zero kinetic energy since we are seeking the minimum speed for escape. Thus Uf = 0 and Kf = 0. And from conservation of energy,
Ki + Ui = Kf + Uf
mv²/2 -GMm/R = 0
∴ v = √(2GM/R)
This is the expression for escape velocity.
There's not enough information given in the problem to calculate that answer.
A leaf falling from a tree on Earth, a sheet of printer paper falling off the back
of a truck on Venus, and a steel ball sinking through a bucket of Scotch whiskey
on Mars, might all reach the bottom in 0.75 second. The time it would take each
of them to fall the same distance through a vacuum in the same place would be
different, and the 0.75 second is not enough to enable you derive it ... <em>even</em> if
you <em>did</em> know the acceleration of gravity in each place. All you can say is that
without resistance, it would fall faster, and hit bottom in <em>less than</em> 0.75 second.
False hypothermia is having an extremely low body temperature.....hope this helps
is there a tutor available
