Answer
See explanation.
Work Step by Step
a. First find the energy density .
$$u=\frac{U}{V}=\frac{B^2}{2\mu_0 }$$
Solve for the volume.
$$V=\frac{2\mu_0 U}{B^2}$$
$$V=\frac{2(4\pi \times10^{-7}Wb/m \cdot A)(3.60\times10^6 J)}{(0.600T)^2}=25.1m^3$$
b. Again find the energy density .
$$u=\frac{U}{V}=\frac{B^2}{2\mu_0 }$$
Solve for the field.
$$B=\sqrt{\frac{2\mu_0 U}{V}}$$
$$B=\sqrt{\frac{2(4\pi \times10^{-7}Wb/m \cdot A)(3.60\times10^6 J)}{(0.400m)^3}}=11.9T$$
