A system absorbs 21. 6 kj of heat while performing 6. 9 kj of work on the surroundings. If the initial internal energy, e, is 61. 2 kj, what is the final value of e?.

Aplanet of mass m 6.75 x 1024 kg is orbiting in a circular path a star of mass m 2.75 x 1029 kg. the radius of the orbit is r 8.05 x107 km. what is the orbital period (in earth days) of the planet tplanet?

Which statement is true? a. kepler's laws apply only to the motion of earth. b. kepler's laws can be used to predict eclipses. c. kepler's laws are true for a central force that is directly proportional to distance. d. kepler's laws can be deduced from newton's laws of motion and gravity.

Why is it important always to use horizontal bars in unit fractions when performing unit conversions?