A hot-air balloon stays aloft because hot air at atmospheric pressure is less dense than cooler air at the same pressure. If the volume of the balloon is 500.0 m^3 and the surrounding air is at 15.0°C. What must the temperature of the air in the balloon be for it to lift a total load of 290 kg (in addition to the mass of the hot air)? The density of air at 15.0°C and atmospheric pressure is 1.23kg/m^3.

272° C

Explanation:

Given :

Volume of the balloon, V = 500

The temperature of the surrounding air,

Total load, = 290 kg

Density of the air,

We known buoyant force,

For a 290 kg lift,  

∴

 ∴

         = 545 K

Therefore, temperature of the air in the balloon is 272 degree Celsius.

work: w = fd (given)

work done by chet   =50*1 = 50 j

work done by mika =40*2 = 80 j

work done by sara =30*1.5 = 45 j

work done by bill =60*0.5 = 30 j

students in order from the greatest amount of work done to the least is mika> chet> sara> bill

hence option (b) is correct.

i think it would be 5