# I have some physics homework questions I need help with?

These are the only 4 questions I am having issues understanding. I have all my other homework questions finished but these ones especially the first one I just do not understand.

1. A brass vat is

11 m

long at room temperature (20°C). How much longer is it when it contains boiling water at 1 atm pressure?

2. An aluminum wing on a passenger jet is

27 m

long when its temperature is

17°C.

At what temperature would the wing be 7 cm (0.07 m) shorter?

3. Air in a balloon does

55 J

of work while absorbing

72 J

of heat. What is its change in internal energy?

4. An apartment has the dimensions 16 m by 8 m by 5 m. The temperature is 25°C, and the relative humidity is 52 percent. What is the total mass (in kg) of water vapor in the air in the apartment?

### 1 Answer

- Anonymous4 weeks ago
1. the change in length is

length * thermal expansion coefficient * change in temp

the change in temp is 80ºC

look up the thermal coefficient for brass

2. same idea; look up coefficient for aluminum

3. 72J - 55J

4. Look up the amount of water vapor for saturation at 25º. Take 52% of that and multiply by the volume of the room.