Helium gas is in a cylinder that has rigid walls. If the pressure of the gas is $2.00 \mathrm{~atm},$ then the root-mean-square speed of the helium atoms is $v_{\mathrm{rms}}=176 \mathrm{~m} / \mathrm{s}$. By how much (in atmospheres) must the pressure be increased to increase the $v_{\mathrm{rms}}$ of the He atoms by $100 \mathrm{~m} / \mathrm{s}$ ? Ignore any change in the volume of the cylinder.