Which of the following changes will always increase the efficiency of a thermodynamic engine? choose all correct statements.

check all that apply.
a. decrease the hot reservoir temperature th while keeping the cool reservoir temperature tc constant.
b. increase the difference th−tc.
c. decrease the ratio tc/th.
d. increase th while keeping tc constant. increase tc while keeping th constant. decrease tc while keeping th constant.

Aray diagram for a refracted light day is shown. what does the dashed line represent

Ablock of steel has a density of 0.29lbs per cubic inch. if the block has dimensions of 1 inch by 1 inch by 3 inches, what is its weight? a. 0.29lbs b. 0.58lbs c. 0.87lbs d. 1lbs

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.