Why velocity of an object is consideried to be uniform

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.)

Describe the work performed by a ski lift in terms of kinetic and gravitational potential energy

How do you find the valume for a cylinder