[填空题]
A certain type of automob a/u-(x /n-z/s;ncb/+ /lxunc ouhestile can accoa/d3) acvg s1 (am:tlelerate approximately as shown in the velocity–time graph of Fig. 2–35. (The short 3(ma:s lv/1aogt)acd flat spots in the curve represent shifting of the gears.)
(a) Estimate the average acceleration of the car in second gear and in fourth gear. The average acceleration in $2^{nd}$ gear is given by $m/s^2$ The average acceleration in $4^{th}$ gear is given by $m/s^2$
(b) Estimate how far the car traveled while in fourth gear. m
