The intensity of a particular earthquake wave is measured to be 9.0 ✕ 106 J/m2·s at a distance of 52 km from the source.
(a) What was the intensity when it passed a point only 2.0 km from the source? J/m2·s(b) What was the rate energy passed through an area of 5.0 m2 at 2.0 km? W
(a) Using the inverse square law, we know that intensity I is proportional to 1/d^2, where d is distance.
Thus, in this case, I2 = I1 * 1/(d1/d2)^2 = 9E6 [J/m^2*s]/(2 [km]/52 [km])^2 = 6.084E9 [J/m^2*s]
You could also think of this as I(2km) = I*A(52km)/A(2km) = 9.0*10^6*4pi*(52^2)/(2^2) = 6.084E9 [J/m^2*s]
(b) Since I = P/A, where I is intensity, P is power, and A is area,
P = I*A = 6.084E9 [J/m^2*s] * 5 [m^2] = 30.42E9 [J/s]
Content will be erased after question is completed.
Enter the email address associated with your account, and we will email you a link to reset your password.
Forgot your password?