Which of these is an example of how engineers have contributed to society

Plz mark brainliest 30 points 1) find the momentum of a 12 kg snowball that is rolling with a velocity of 9 m/s. 2) an 8 ball with a mass of .5 kg is sitting at rest. it is hit by the cue ball (1 kg) traveling at 2.5 m/s. if the cue ball is at rest after the collision, how fast is the 8 ball traveling after the collision? 3) two football players are running toward each other. if the offensive player is 75 kg and is running 8 m/s, how fast must the 60 kg defensive player run in order for the two players to hit and stop?

What is the most common reason for matter changing its state?

Ablock of aluminum is dropped into a graduated cylinder with an initial volume of water at 75ml and the volumes rises to 90ml. if the block has a mass of 40.5 g what is its density ?