physics help!!!! I can't figure these problems out and I have a test tomorrow?

[deathlyhallows789]

1. the earth orbits the sun once a year at a distance of 1.5E11. Mars orbits the sun at a distance of 2.3 E 11 m. approximately how long in earth days does it take fro mars to make ne orbit around the sun?


2. A water slide constructed so that swimmers, starting from rest at the top of the slide, leave the end of the slide traveling horizontally in such a slide, one person hits the water 10.0 m from the end of the slide in 2s after leaving the slide. what i s the height of the slide in meters?

3. consider a skier on an inclined plane of height 100,. the frictional force acting on the skier is 40 N what is the speed of the skier in m/s as she touches the ground? use the work-energy theorm

4. consider a roller coaster, if the speed at a height of 50m is 20 m/s, what is the speed in m/s at a height of 25 m?