i have to say physics kicks my butt. i never worked so hard in my life to earn a D in a class. now, i have to take the lab for that course and they are trying to kill us! the TA tore up my lab partners work because he didn't like the way she presented it in her lab book! ok, so that is what i am dealing with here. plus if i don't pass this i can't graduate this semester. i need some help on the following: 1 . What is the gravitational potential energy of a ball on Mars with a weight of 56.3 N when it is sitting on a shelf 17.64 m above the Martian floor? my attempt: PE=mgh gravity on mars according to wiki= 3.69m/s^2 PE= 5.63 X 17.64 X 3.69 = 3664.7 2 . Suppose you are performing the downhill run of the experiment you did this week, what is the energy ratio (Ef/Ei) of a system on Ganymede that has a final velocity of 996.9 cm/s, initial velocity of 8.8 m/s, and a height of 0.0748 km. Assume that the gravity on Ganymede is 1.428 m/s2. my attempt: no clue where to start 3 . Two cars have the same mass, but the red car has 4.55 times the velocity of the blue car. What is the kinetic energy ratio of the blue car to the red car? Express as Kr/Kb= ? . my attempt: again no clue where to start. 4 . An astronaunt lands on the dwarf planet Eris and decides to perform experiments. One of these experiments is to measure the acceleration due to gravity. He finds that the acceleration due to gravity is constant at 0.8 m/s2. Then he finds a deep crater and wants to know its depth so he fires a rope to the center of the crater. He then slides down the rope without friction and finds that his velocity at the bottom is 70.97 ± 0.3 m/s. Using this information and the fact that the astronaunt has a weight with his suit of 240 N on Mars, find the average depth of the crater. my attempt: a= 0.8m/s2 ; d=? Vo= 0m/s ; Vf= 70.97m/s; m= 240N to me the most relivant equation is Vf2= Vo2 + 2ad (70.97)2= (0)2+ 2(.8)(d) (70.972)/(2*.8)=d 3147.9m = d 5 . The space shuttle is the most complex machine ever built and the first orbital spacecraft designed for partial reusability. It has a mass of 2,209,203 kg and is capable of taking up to 11 astronaunts and 24,400 kg of payload into orbit. For it to achieve orbit, it takes an average $450 million and a two stage rocket capable of delivering 5,253 kN of thrust. Once in orbit, it must maintain a speed of 17,500 mph. When the space mission is over, the shuttle must dissipate all of the energy in the form of heat (friction) by performing a series of S turns. Assuming the shuttle lands at 246.8 mph, has 4 astronaunts each with a weight of 200 kg, and a payload weight of 22847 kg, find how much energy (in GJ) the shuttle has the second that it lands (does not come to a complete stop). my attempt: huh?