1. A force of 256 N is used to push a 182kg mass 74m horizontally in 1.3s. Calculate the work done in Joules on the mass. Answer in units of J. 2. Calculate the power in kW.

The radioactive isotope of lead, pb-209, decays at a rate proportional to the amount present at time t and has a half-life of 3.3 hours. if 1 gram of this isotope is present initially, how long will it take for 80% of the lead to decay? (round your answer to two decimal places.)