Suppose that the resistivity (p) of a certain material various with its tem- perature (T) in accordance to the following quadratic equation a(T) p (1 + α(T-T) + β(T-TO)2) with T0 = 20°C and po = 500 nQ-m. Suppose also that the resistivity of this material is found to drop to one half its value at T0 when T1 =-100°C and suppose that the material is found to become superconducting when T2270°C. Determine the resistivity of this material when T 0°C. (a) 154 ns. m (b) 254 n2.m (c) 354 n2 m (d) 454 n2 m (e) 554 ns2 .m (f) None of the above.

An insurance company wants to know if the average speed at which men drive cars is higher than that of women drivers. the company took a random sample of 27 cars driven by men on a highway and found the mean speed to be 72 miles per hour with a standard deviation of 2.2 miles per hour. another sample of 18 cars driven by women on the same highway gave a mean speed of 68 miles per hour with a standard deviation of 2.5 miles per hour. assume that the speeds at which all men and all women drive cars on this highway are both approximately normally distributed with unknown and unequal population standard deviations.

Modern physics a photon emitted from an excited hydrogen atom has an energy of 3.02 electron volts. which electron energy-level transition would produce this photon? a. n=1 to n=6 b. n=2 to n=6 c. n=6 to n=1 d. n=6 to n=2 i chose b but the correct answer is d can someone tell me why? and what's the difference?

Abookcase has a mass of 38 kg and the coefficient of friction between it and the floor is 0.82 what is the maximum force of friction between the bookcase and the floor a 372n b 305n c 412n d 449n