A roofer needs to get shingles onto a roof. Pulling the shingles up manually uses 1,549 N or force. The roofer decides to use a system of pulleys. Using the pulleys, 446 N are required to lift the shingles. What is the mechanical advantage of the system of pulleys?

Abeam of electrons with of wavelength of 7.5 x 10-6 m is incident on a pair of narrow rectangular slits separated by 0.75 mm. the resulting interference pattern is projected onto a screen 10.0 m from the slits. what is the separation of the interference maxima in the resulting interference pattern?

Explain the difference between each pair of concepts. a. frequency and relative frequency b. percentage and relative frequency a. select the correct choice below. a. frequency is the total number of observations in a data set. relative frequency is the number of times a particular distinct value occurs. b. frequency is the number of times a particular distinct value occurs. relative frequency is the ratio of the frequency of a value to the total number of observations. c. frequency is the total number of observations in a data set. relative frequency is the ratio of the number of times a particular distinct value occurs to the frequency. d. frequency is the number of times a particular distinct value occurs. relative frequency is the ratio of the frequency of two different values.

Which of the following are considered noble gases? a. bromine b. neon c. argon d. chlorine