In real life a roller coaster has 20,000 Joules of Potential Energy at the top of a hill. How much Kinetic Energy does it have at the bottom of the hill? a.)40,000 J
b.)Less than 20,000 J due to Friction
c.)Exactly 20,000 J due to Friction
d.)0 J

The gun from the crime scene shows tool marks where the serial numbers are ground off. there are also tool marks on the bullets left behind. what information can the tool marks on the bullets and gun provide about the crime? what type of evidence does this information provide, individual or class?