100 points
you are out and about in the country and your father sees a rock that he really wants in the yard. now you must get the very heavy rock into the back of a truck. the truck bed is 3 feet off the ground. your father pulls out a 5-foot plank and begins to set up a ramp. at the same time, you (who know about mechanical advantage! ) have found a plank that is 8 feet long, and you show it to your father. which plank will give you the most mechanical advantage? calculate the ma for each plank.

You have been called to testify as an expert witness in a trial involving a head-on collision. car a weighs 1515 lb and was traveling eastward. car b weighs 1125 lb and was traveling westward at 44.0 mph. the cars locked bumpers and slid eastward with their wheels locked for 22.5 ft before stopping. you have measured the coefficient of kinetic friction between the tires and the pavement to be 0.750 . how fast (in miles per hour) was car a traveling just before the collision? (this problem uses english units because they would be used in a u.s. legal proceeding.)

To travel at constant speed, a car engine provides 24kw of useful power. the driving force on the car is 600n. at what speed does it travel?

Calculate the amount of heat produced when 18000 coulombs of charge is transferred in one hour through a potential difference of 50v