Rotational physics conceptual questions

[MozAngeles]

Homework Statement

A motorcycle accelerates from rest, and both tires rotate without slipping.
1. Is the force exerted by the ground on the rear tire in the forward or backward direction?explain.
2. Is the force exerted by the ground on the front tire in the forward or backward direction? explain
3. If the moment of inertia of the front tire is increased, will the motorcycle's acceleration increase, decrease, or remain the same?explain
any help would be nice please thankssss

Homework Equations

The Attempt at a Solution

1. I put...forward because The frictional force is acting on the tire in the forward direction to keep it from slipping.
2.forward for the same reason
3.decrease because the bigger the moment of inertia the slower it will go
i don't know it my answers and or reasoning are right.. Can someone steer me in the right direction.

 

[zhermes]

You're exactly right on all three.

Another way to think about 1 and 2: the reason why the car accelerates is because the external force (friction from the ground) is exerted in the forward direction.