The average human lung expands by about 0.51 L during each breath. Part A If this expansion occurs against an external pressure of 0.90 bar, how much work (in J) is done during the expansion? Express your answer in joules to two significant figures. Work=square J

Here's how to calculate the work done during lung expansion:<br /><br />**Understanding the Concept**<br /><br />Work done by a system against a constant external pressure is given by the formula:<br /><br />Work (W) = -P_ex * ΔV<br /><br />Where:<br /><br />* P_ex is the external pressure<br />* ΔV is the change in volume<br /><br />**Calculations**<br /><br />1. **Convert pressure to Pa:** 1 bar = 100,000 Pa. So, 0.90 bar = 0.90 * 100,000 Pa = 90,000 Pa<br /><br />2. **Convert volume to m³:** 1 L = 0.001 m³. So, 0.51 L = 0.51 * 0.001 m³ = 0.00051 m³<br /><br />3. **Calculate the work:** W = - (90,000 Pa) * (0.00051 m³) = -45.9 J<br /><br />4. **Consider significant figures:** The problem asks for the answer to two significant figures. Therefore, the answer is -46 J.<br /><br />**Answer:**<br /><br />Work = -46 J (The negative sign indicates work is done *by* the system, i.e., the lungs.)<br />