All magnets must have exactly two poles, one north and one south. Explain how scientists determine the poles of an unlabeled magnet

Arescue plane flying horizontally at spots a survivor in the ocean directly below and releases an emergency kit with a parachute. because of the shape of the parachute, it experiences insignificant horizontal air resistance. if the kit descends with a constant vertical acceleration of, how far away from the survivor will it hit the waves?

The percent efficiency of a machine can never be 100% (or greater), because in the real world some energy is always converted into a. heat b. work c. input force d. output force

Consider an ordinary, helium-filled party balloon with a volume of 2.2 ft3. the lifting force on the balloon due to the outside air is the net resultant of the pressure distribution exerted on the exterior surface of the balloon. using this fact, we can derive archimedes’ principle, namely that the upward force on the balloon is equal to the weight of the air displaced by the balloon. assuming that the balloon is at sea level, where the air density is 0.002377 slug/ft3, calculate the maximum weight that can be lifted by the balloon. note: the molecular weight of air is 28.8 and that of helium is 4.