Astudent designs an experiment where he takes a small wood car with 1.0 inch diameter wheels and rolls it down a ramp. the student measures the speed of the car when it reaches the bottom of the ramp. the student then takes a small plastic car with 1.5 inch diameter wheels and repeats the process. finally, the student takes a small metal car with 2.0 inch diameter wheels and repeats the process a final time. the student notes that the metal car had the fastest speed at the bottom of the ramp. the student can conclude:

As the radius of a wheel , in rolling motion on a inclined plane, changes , its final speed , does not change . In other words , acceleration of wheel on inclined plane does not depend upon radius of the wheel . It also does not depend upon the mass of the wheel.

Explanation:

In case of perfect rolling on an inclined plane, the acceleration of body is given by the following expression.

a = g/1+k²/r² where k is known as radius of gyration . For a wheel its value is equal to( 1/√2)r.r is radius . From this expression , one can conclude that acceleration and therefore velocity does not depend upon radius of the wheel . Therefore the reason of the metal car having greatest speed  is the resistance of air and friction of surface being the least in its case.

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%