Clinical laboratory procedure; answer the question?

A clinical laboratory procedure requires that a urine sample be centrifuged for 8 minutes at 5000 x g in a centrifuge with a rotating radius of 30 cm. What speed (rpm) should be used to attain this?

A clinical laboratory procedure requires that a sample be centrifuged at 6000 x g for 10 minutes. What duration of time would be needed to attain an equivalent force using another centrifuge that can achieve a maximum force of 2600 x g?