A tight metal lid on a jar of pickles may loosen when it has been held in hot water. This is because the hot water causes the

metal lid to expand more than the glass jar expands

Which unit is used to indicate the amount of energy in food?

calorie

Frank needs to move a box by sliding it across the floor. Which two factors will most strongly affect how hard Frank needs to push the box?
The total mass of the box and the friction between the box and the floor