Ahmed saw all of these things as he walked to school this morning. Which one is an example of a force pushing downward toward the ground?

A. A bird sat on a telephone wire.
B. A woman moved her child from one place to another in a wagon.
C. A man pulled weeds in his garden.
D. A dog tugged on a rope a child held.

Estimate the kinetic energy of mars with respect to the sun as the sum of two terms, that due to its daily rotation about its axis, and that due to its yearly revolution about the sun. (assume mars is a uniform sphere with mass = 6.4×10 to the power of 23 kg, radius = 3.4×10 to the power of 6 m, rotation period = 24.7 hours, orbital period = 686 days and is 2.3×10 to the power of 8 km from the sun.)