Apiece of spacecraft debris initially at rest falls to the earth's surface from a height above the earth equal to one-half of the earth's radius. find the speed at which the piece of debris hits the surface. neglect air resistance and the gravitational pull of the moon. express your answer with the appropriate units.

7.65 X 10^12 m/s

Explanation:

When the debris falls, at that instance P.E = K.E

mgh=mv^2/ 2

mass of the earth= 5.972 × 10^24

height=5.972 × 10^24/2

Height h= 2.986 × 10^24

V=√(2gh)

V= √(2 * 9.8 * 2.986 *10^24)

V= 7.65 X 10^12 m/s

radiation

explanation:

heat is transmitted by radiation

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.