If a spring stores 20 J of energy when it's compressed by 0.4, what is the spring constant of the spring?

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.)

Which changes of state do the labels represent? a: b: c:

In positive numbers less than 1, the zeros between the decimal point and a non-zero number are blank significant