Aboy and girl on ice skates face each other. the girl has a mass of 20 kg and the boy has a mass of 30 kg. the boy pushes the girl backward at a speed of 3.0 m/s as a result of the push the speed of the boy is

20 x 3 = 60

60/30 = 2

 the speed of the boy would be -2 m/s

wavelength variability is the right one

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.