If a snail travels at 5 m/s, how far will it travel in 90 seconds?

Due in 40 explain in terms of frame of reference if you’re inside a moving train everything on the outside can seem to be moving

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.)

Consider lifting a box of mass m to a height h using two different methods: lifting the box directly or lifting the box using a pulley (as in the previous part). what is wd/wp, the ratio of the work done lifting the box directly to the work done lifting the box with a pulley?