Answer:
A) If the paintball stops completely the magnitude of the change in the paintball’s momentum is 
B) If the paintball bounces off its target and afterward moves in the opposite direction with the same speed, the change in the paintball’s momentum is 
C) A paintball bouncing off your skin in the opposite direction with the same speed hurts more than a paintball exploding upon your skin because of the strength exerted is twice than if it explodes.
Explanation:
Hi
A) We use the formula of momentum
, so we have 
B) We use the same formula above, then due we have a change of direction at the same speed, therefore the change in the momentum is the double so
.
C) The average strength of the force an object exerts during impact is determined by the amount the object’s momentum changes. therefore
, as we don't have any data about the impact time but we know momentum is twice, time does no matter and strength is twice too.
The kinetic energy bc the energy is independent of the gravitational acceleration, and it depends only on the speed and mass. So the last answer
The orbital radius is: 
Explanation:
The problem is asking to find the radius of the orbit of a satellite around a planet, given the orbital speed of the satellite.
For a satellite in orbit around a planet, the gravitational force provides the required centripetal force to keep it in circular motion, therefore we can write:

where
G is the gravitational constant
M is the mass of the planet
m is the mass of the satellite
r is the radius of the orbit
v is the speed of the satellite
Re-arranging the equation, we find:

Learn more about circular motion:
brainly.com/question/2562955
brainly.com/question/6372960
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In this case, you need the formula below where:
F = force
k = coulombs constant 8.99 x10^{9} N.m^{2} . C^{-2}
q1 = electric charge 1
q2 = electric charge 2
r = the distance between the charges

pls note: make sure your units are correct (in meters etc, not fm (<em>femto-meters</em>)).
Curiously, this question doesn't tell you what atom you are next to the nucleus of. Different numbers of protons in the nucleus of the atom will make for vastly different forces in your answer...
It would be kinetic energy. Let's say the book is weighs 10 Newtons you need to use a force of 10 Newtons to lift the book. In other words it's positive. As you move the book you're giving it energy. Namely potential energy which will turn to kinetic energy if you let it go. So you're changing it's position and energy.