How much work is done in raising a 12.1 kg backpack from the floor to a shelf 1.64 m above the floor?

answer:   you might love summer weather, but you don’t want it to feel like the sun is inside your car. but a hot car that just won’t seem to cool down might be a bigger of a problem than you think. your car relies on being at the right temperature.

explanation:

double the distance = divide strength by 4

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