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

.
For #5 It's helpful to draw a free body diagram so you know which way the forces are acting on the block.
the weight mg is acting downwards, and you need to find the vertical and horizontal components of mg using sin and cosine. so do 15x9.8xsin40 which is the force. Assuming no friction, this is the only force acting on the block, as the forces on the vertical plane cancel out i.e the normal force and weight of the block.
after, just do F=ma And since you know F and m, solve for a.
I believe the answer would be Kinetic Energy. Kinetic energy is defined as energy which a body possesses by virtue of being in motion. We weren’t given answer choices so I don’t have much to work with lol.
Answer: we can ues all the time
Explanation: and have fun with it