The mass of a hot-air balloon and its occupants is 260 kg (excluding the hot air inside the balloon). The air outside the balloon has a pressure of 1.01 105 Pa and a density of 1.29 kg/m3. To lift off, the air inside the balloon is heated. The volume of the heated balloon is 600 m3. The pressure of the heated air remains the same as the pressure of the outside air. To what temperature (in Kelvins) must the air be heated so that the balloon just lifts off?

Which car has the most kinetic energy? a. a car of mass 1000 kg with a speed of 3 m/s b. a car of mass 2000 kg with speed 7 m/s c. a car of mass 1000 kg with speed 7 m/s d. a car of mass 2000 kg with speed 3 m/s

Which radioisotope is used in dating geological formations?

Materials will have different energies associated with the electrons inside them. this is related to how strongly bound they are by their work function. if we sandwich a material with a very low energy between two materials with a high energy, we create a trap for an electron. if this trap is very narrow in one direction in comparison to the others, this is approximately a 1-dimensional box that confines the electron. what is the lowest energy of an electron in the box if the thinnest direction across the materials is 4.81 nm?