Moment of Inertia?

Homework Statement

Suppose you are designing a car for a coasting race -- the cars in this race have no engines, they simply coast down a hill. Do you want large wheels or small wheels? Do you want solid, disk-like wheels, or hoop-like wheels? Should be wheels be heavy or light? (Select all that apply. Omit both choices in a pair if neither have a beneficial effect.)

Homework Equations

Moments of Inertia:
Hoop or thin cylindrical shell:
I=MR2
Solid cylinder:
I=(1/2)MR2

The Attempt at a Solution

The options are:

large
small
solid, disk-like
hoop-like
heavy
light

So I guessed small; solid, disk-like; and light because according to those equations above, those options would make it have a lower moment of inertia… but according to webassign, that is wrong, and I do not understand why. Can someone help?

Related Introductory Physics Homework Help News on Phys.org
Well a lower moment of inertia would mean less resistance to motion right? so it would move more quickly? and yes this is related to the other question… Am I approaching it right by using moment of inertia?

Simon Bridge
Homework Helper
Linear inertia = mass.
You have a race between two blocks mass M and m with M>m sliding down a frictionless slope. Which one reaches the bottom first: the one with the big inertia or the one with the small inertia?

hmm the one with the small inertia?

Simon Bridge
Homework Helper
Do the free body diagram for sliding down a slope angle ##\theta## to the horizontal.

okay so FN=mgcosθ and ma=mgsinθ

Simon Bridge
Homework Helper
... so which mass reaches the bottom first?

they reach the bottom at the same time?

Simon Bridge