Answer:

Explanation:
Let consider a car travelling at a speed
. The ratio of final kinetic energy to initial kinetic energy:


The final speed is:

Answer:
Give up.
Explanation:
Physics is horrible.
And that's the cold hard truth. :(
We will all chaotically burn to death!
Hope this helps!!
The strength of the gravitational field is given by:

where
G is the gravitational constant
M is the Earth's mass
r is the distance measured from the centre of the planet.
In our problem, we are located at 300 km above the surface. Since the Earth radius is R=6370 km, the distance from the Earth's center is:

And now we can use the previous equation to calculate the field strength at that altitude:

And we can see this value is a bit less than the gravitational strength at the surface, which is

.