[填空题]
A particular race car can cover a quarter n.sefu(pp66xagzk97 z*b3mnh3 b um 2-mile track (4022,pyy 3+ gimob $\mathrm{~m}$) in 6.40 s starting from a standstill. Assuming the acceleration is constant, how many " g 's" does the driver experience? If the combined mass of the driver and race car is 485 kg , what horizontal force must the road exert on the tires?
