6. A billiard ball traveling at 4.0 m/s has an elastic head-on collision with a billiard ball of equal mass
that is initially at rest. The first ball is at rest after the collision. What is the speed of the second ball
after the collision?
A) 4.0 m/s
B) 8.0 m/s
C) Not enough information to solve this problem
D) 4.0 kg m/s

Thomas his older brothers, who own a junk yard, on the weekends to earn extra money. he likes to them push broken-down cars to the back of the junk yard because it makes him feel strong. last saturday, they pushed three cars with different weights, and he noticed he used different amounts of force for each one. the cars were the following weights: white car: 2,700 kg red car: 1,500 kg blue car: 2,100 kg think about how much force is needed to move each car. which correctly lists the cars in order from the most to least amount of force needed to move them? a) white, blue, red b) blue, red, white c) red, white, blue d) white, red, blue