Which of the following is an accurate statement? a. ac generators produce current that is pulsating, but always remains positive. b. step-down voltage transformers have a different number of turns in the primary than in the secondary winding, so they change the incoming voltage to a higher voltage. c. dc generators produce current with a voltage that changes from positive to negative. d. step-up voltage transformers have a lower number of turns in the primary than in the secondary winding.

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.

Awoman holds a book by placing it between her hands such that she presses at right angles to the front and back covers. the book has a mass of m = 1.8 kg and the coefficient of static friction between her hand and the book is μs = 0.67. no attempt 50% part (a) what is the weight of the book, fgb in newtons?

What is the role of lenses in microscopy?