Radioisotopes are used in a variety of manufacturing and testing techniques. Wear measurements can be made using the following method. An automobile engine is produced using piston rings with a total mass of 100 g, which includes 9.4 mCi of 5ºFE whose half-life is 45 days. The engine is test-run for 1500 hours, after which the oil is drained and its activity is measured. If the activity of the engine oil is 3.72 x 103 decays/s. (b) What would be the activity in the piston after 0.0802 grams has been worn off the piston?

Radioisotopes are used in a variety of manufacturing and testing techniques. Wear measurements can be made using the following method. An automobile engine is produced using piston rings with a total mass of 100 g, which includes 9.4 mCi of 5ºFE whose half-life is 45 days. The engine is test-run for 1500 hours, after which the oil is drained and its activity is measured. If the activity of the engine oil is 3.72 x 103 decays/s. (b) What would be the activity in the piston after 0.0802 grams has been worn off the piston?