Answer:
This is very hard bit I think 6.3 my, I'm not shure.
Answer:
a. negative
b. zero
Explanation:
work is the change in the energy of a system due to external forces
work is done when a force moves a load through a distance in the direction of the force
The work done by a force on a system is positive when the force and the force displacement point in the same direction and negative when they point in opposite directions
in the scenario we are considering in the question, the force (the hand) moves the block vertically upwards but the displacement of the block reduces (in the opposite direction) since it decelerates. as such the work done by gravity on the block is negative.
the work done on the block is zero if the system consists of the block and the earth because there is no gravitational force exerted on the system
Answer:

Explanation:
The gravitational potential at a point on the Earth surface is given by:

where
G=6.67×10^-11Nm^2kg^-2 is the gravitational constant
M=5.98×10^24kg is the Earth's mass
R=6.38×10^6 m is the Earth's radius
Substituting the numbers into the equation, we find

When an object is moving with uniform circular motion, the centripetal acceleration of the object d. is directed toward the center of motion.
You don't have a following space exploration