What is the kinetic energy ( during free fall) when height is 0m. Plz explain properly

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.)

If one object has a large redshift and another object has a small redshift, what can we conclude about these two objects?

Acarpenter is driving a 15.0-g steel nail into a board. his 1.00-kg hammer is moving at 8.50 m/s when it strikes the nail. half of the kinetic energy of the hammer is transformed into heat in the nail and does not flow out of the nail. what is the increase in temperature of the nail after the three blows that the carpenter needs to drive the nail in completely? the specific heat of steel is 448 j/kg ∙ k. a) 2.7 k b) 1.8 k c) 7.7 k d) 8.1 k e) 3.6 k