You apply a 150 N push on a frictionless sled over a period of 2 seconds. Show that the sled’s momentum changes by 300 kg·m/s.

Honestly "global warming" may be a slight possiblity, however they called it "climate change" because its not real, in fact we had one of our coldest days here not too long ago, and the "issues" with this subject is a blindfold for actual problems.

You would need to take a picture so i can see

Newtons laws of motion

Answer(a)   the matererials that are in contact, the two materials and the nature of their surfaces/// (b)/// the force pushing the two surfaces together, pushing the surfaces together causes the more of the asperities to come together and increases the surface area in contact with each other