Which form of energy is responsible for the primary energy output of the sun and other stars? (points : 1)
chemical energy
nuclear energy
mechanical energy
electromagnetic energy

On the sun it's nuclear energy. The sun gets so hot that fusion occurs; when atoms are joined together either from extreme heat or force. In the sun's case, both extreme force from the sun's raging gasses and and heat from the searing hydrogen and helium are contributing to the fusion process.

It's 'rays' are electromagnetic.

W= fd
where f is an applied force and d is the distance over which it is applied. when a parachuting skydiver is at constant velocity, he is experiencing "terminal velocity", the point at which his acceleration down is canceled out by air resistance. that means that the resisting force of the air is equal to his weight, but in the opposite direction. with this, we can solve for the work done by the force.
w = fd
w = (92.0)(9.81 m/s^2) (325)
w= 2.93 x 10^5 j
the value for work in this case is positive because it is pushing up on the skydiver, who has a downward force of gravity.
therefore the answer is 2.93 x 10^5 j