[填空题]
Amtrak’s high speed train, the Acela, util90v .eiy,cdmfi qf5chv; 3i.sizes tilt of the c 5fzufa/ :,us1 fgj1dxu n52iaars when negotiating curves. The angle of tilt is adjusted so that the main force exerted on the passengers, to gus1d 12ju: a,/ 55nzfauff xiprovide the centripetal acceleration, is the normal force. The passengers experience less friction force against the seat, thus feeling more comfortable. Consider an Acela train that rounds a curve with a radius of 620 m at a speed of (approximately ). (a) Calculate the friction force needed on a train passenger of mass 75 kg if the track is not banked and the train does not tilt. $\approx$ $\times 10^2$
(b) Calculate the friction force on the passenger if the train tilts to its maximum tilt of 8.0º toward the center of the curve.$\approx$ $\times 10^2$
