Answer:
KE = 1/2 M v^2 kinetic energy of projectile
KE = 1/2 * 20 * (54 m/s)^2 = work done on projectile
W = 10 * 54^2 = work done on projectile
W = 29,160 J
Answer:
The object would weight 63 N on the Earth surface
Explanation:
We can use the general expression for the gravitational force between two objects to solve this problem, considering that in both cases, the mass of the Earth is the same. Notice as well that we know the gravitational force (weight) of the object at 3200 km from the Earth surface, which is (3200 + 6400 = 9600 km) from the center of the Earth:

Now, if the body is on the surface of the Earth, its weight (w) would be:

Now we can divide term by term the two equations above, to cancel out common factors and end up with a simple proportion:

When a force acts (pushes or pulls) on an object, it changes the object's speed or direction (in other words, makes it accelerate). The bigger the force, the more the object accelerates. When a force acts on an object, there's an equal force (called a reaction) acting in the opposite direction.