help me plsss, this is worth 30 points!! can someone pls help even if u can only give a few answers it would be helpful.

If steel is more dense that lake water, why can a boat float

(a) assume the equation x = at^3 + bt describes the motion of a particular object, with x having the dimension of length and t having the dimension of time. determine the dimensions of the constants a and b. (use the following as necessary: l and t, where l is the unit of length and t is the unit of time.) (b) determine the dimensions of the derivative dx/dt = 3at^2 + b. (use the following as necessary: l and t, where l is the unit of length and t is the unit of time.)

Amira pulls a 3 pound wagon 4 feet. how much work has she done?