Which of the following describes the net force acting on an object?

A. The sum of all forces acting on an object
B. The gravitational force minus any contact forces acting on an object
C. The difference between the normal force and the gravitational force acting
on an object
D. The sum of all the forces acting on an object in the same direction

10. according to the law of conservation of mass, how does the mass of the products in a chemical reaction compare to the mass of the reactants?

Hot air balloons float in the air because of the difference in density between cold and hot air. in this problem, you will estimate the minimum temperature the gas inside the balloon needs to be, for it to take off. to do this, use the following variables and make these assumptions: the combined weight of the pilot basket together with that of the balloon fabric and other equipment is w. the volume of the hot air inside the balloon when it is inflated is v. the absolute temperature of the hot air at the bottom of the balloon is th (where th> tc). the absolute temperature of the cold air outside the balloon is tc and its density is ďc. the balloon is open at the bottom, so that the pressure inside and outside the balloon is the same. as always, treat air as an ideal gas. use g for the magnitude of the acceleration due to gravity.

Drive down any three characteristic of modern periodic table