How can you evaluate the validity and reliability of claims about the effects of radiation on matter?

Plss anybody know how to do this? ? i need the answers from a through d

After a big snowfall, you take your favorite rocket-powered sled out to a wide field. the field is 195 m across, and you know that your sled accelerates at a rate of 3.65 m/s2 when the rocket is on. how much time will it take the sled to cross the field starting from rest, assuming the rocket is on the whole time?

The free body diagram shows a box being pulled to the left up a 25-degree incline. the magnitude of the normal force is