What 2 things need to be known about an object in order to determine its kinetic energy?

A1200 kg car traveling north at 10 m/s is rear-ended by a 2000 kg truck traveling at 30 m/s. what is the total momentum before and after the collision?

After a big snowfall, you take your favorite rocket-powered sled out to a wide field. the field is 195 m across, and you know that your sled accelerates at a rate of 3.65 m/s2 when the rocket is on. how much time will it take the sled to cross the field starting from rest, assuming the rocket is on the whole time?

Suppose the house in question 3 is located in cleveland where the annual average solar flux is 160 w/m2 . if 10 m2 of solar panels operating at 20 percent efficiency were installed on this house to collect and store solar energy in the form of hot water: