A 10.0-kilogram ball rolling along a flat surface starts up a hill. If the ball reaches a height of 1.0 meters, 4.43 m/s 3.51 m/s 4.2.7 m/s 7.58 m/s

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.

i believe the answer would be:

d. violin, clarinet, french horn, and tuba

there are no contact forces mentioned on the list of choices that you've provided.