Why are some materials magnetic and not others ?

10. a person with a mass of 15 kg is walking uphill at a velocity of 2 m/s. what is the walker's momentum? a. 15 kg-m/s b. 30 kg-m/s c. 10 kg-m/s d. 13 kg-m/s 16. two bouncy balls colliding with each other is an example of what type of collision? a. inelastic collision b. elastic collision c. parallel collision d. mass collision 20 which of the following is considered to be a vector? a. temperature b. mass c. velocity d. time