How is the exposure rate generally expressed?
a. in roentgens per hour
b. in gray
c. in radiation absorbed dose
d. in microcurie

a. in roentgens per hour  

Explanation:

Exposure rate is the ratio of radiation exposure per unit of time. It is often used to measure radiation fields in the environment of a radioactive facility for exposure prevention and control. Exposure rate is generally expressed as per hour roentgens (R / h) used for X-ray or Gamma in air.

The röntgen or roentgen (R) is a unit of exposure to ionizing radiation. The name was given as a tribute to the German physicist Wilhelm Conrad Röntgen (or Roentgen) (1845-1923) who discovered X-rays.

falling water hydro = water .. spectcular places these plants are

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.