Chapter 29, Problem 28A

Wheels from a toy cart are rolled from a concrete sidewalk onto the following surfaces.

(A) a paved driveway

(B) a grass lawn

(C) close-cropped grass (like that on a golf-course putting green)

Due to slowing, each set of wheels bends at the boundary and is deflected from its original course. Rank the surfaces according to the amount each set of wheels bends at the boundary, from greatest amount of bending to least amount of bending.

To determine

To discuss: The rank of surfaces .

Answer to Problem 28A

Rank of the surfaces: B, C, A

Explanation of Solution

Introduction: Angle of reflection is equals to angle of incidence. The law of reflection applies to both, totally reflected waves and partially reflected.

When the toy cart passes between two surfaces then the amount of its wheels is deflected and also, it will be deepened on the change in its speed (b/w wo surfaces). The larger speed change between concrete sidewalk and second surface is more than the deflected wheels.

According to the question, first surface, no changes are excepted because the way is so smooth. In second surface, significant changes are excepted because there is grass in the path. In third figure surface, speed to slow down not as much as the grass lawn, but more than the paved driveway is expected. So, the rank of surfaces is B (a grass lawn), C (Close-cropped grass), A (A paved driveway).

Conclusion: B, C, A is the rank of given surfaces.