Determine the length that a lead shield should have in order to to stop 99% of a beam of γ-rays of 0.5 MeV. (λ1/2 (γ, Pb)= 0.42 cm.)

Which of the following is not a part of the respiratory system? a. pharynx b. trachea c. pancreas d. larynx

Which two particles are found in the center of an atom

6–43 a food department is kept at 2128c by a refrigerator in an environment at 308c. the total heat gain to the food department is estimated to be 3300 kj/h and the heat rejection in the condenser is 4800 kj/h. determine the power input to the compressor, in kw and the cop of the refrigerator.