[填空题]
A cyclist accelerates from rest at a rat6wwy vaaw o;6k4 dld -u3ksx(,e of 6 cwu+bmat1yw6x t,8u1 m/$s^2$ How fast will a point on the rim of the tire at the top be moving after 3.0 s? [Hint: At any moment, the lowest point on the tire is in contact with the ground and is at rest — see Fig. 8–51.] $m/s$