Anyone can help me this question of physics? Thanks!

送交者: hopelessless 于 2016-04-29, 15:35:10:

A bike and a bus travel at the same speed of 20 kilometers per hour on a road. Suddenly, a deer appears in the front of the road. Assuming the bike and the bus hit the breaks at the same time, which one (bike or bus) stops first?

所有跟贴:

理论上一样的时间/距离（假设轮胎和地面的摩擦系数一样） - 北极 (96 bytes) 2016-05-01, 10:28:01 (806760)
取决于刹车力和质量的比率 - html (16 bytes) 2016-04-30, 00:37:08 (806711)
man, many many uncertainties. - cornbug (38 bytes) 2016-04-29, 16:04:33 (806682)
- 没错。bike和bus都有可能刹车不灵or车轮打滑。 (无内容) - 095 (0 bytes) 2016-04-29, 16:22:57 (806687)
我的物理没有meiyou好, 我怎么觉着自行车先停下呢? 惯量和阻力 - silxirt (17 bytes) 2016-04-29, 16:04:11 (806681)
Same time 胡克定律说摩擦力与压力正比所以加速度相同 (无内容) - meiyou (0 bytes) 2016-04-29, 15:47:08 (806678)
- 如果我问要让bike和bus停下所需的力那个大，应该是汽车所需的力大，对不？ (无内容) - hopelessless (0 bytes) 2016-04-29, 16:17:00 (806685)
  - 停下来有个时间因素，定量守恒你也不知道？ (无内容) - meiyou (0 bytes) 2016-04-29, 22:16:10 (806708)
  - 因为汽车的质量大，但是人所需的力汽车小，BIKE大，是吗？ (无内容) - hopelessless (0 bytes) 2016-04-29, 16:19:43 (806686)
    - this is more specific. Yes, M大惯性大。大屁股一扭起来难停下。 (无内容) - cornbug (0 bytes) 2016-04-29, 16:24:16 (806688)
      - BUT, 问题是问那个先停下，难道所用的力小就先停下？ (无内容) - hopelessless (0 bytes) 2016-04-29, 16:28:20 (806689)
        
        比如说汽车刹车力大到像是撞墙而摩托刹车力像撞上个肥屁股，你说谁先停。 - cornbug (23 bytes) 2016-04-29, 16:35:28 (806692)
        
        汽车和BIKE使用的力小，并不等于人用的力小 (无内容) - hopelessless (0 bytes) 2016-04-29, 16:30:46 (806690)
        
        Sorry, (say again) the force needed by bike is smaller than that of bus, BUT... - hopelessless (57 bytes) 2016-04-29, 16:35:10 (806691)
        
        No. a foot brake is eletrohydraulically augmented. human force is irrelevant. (无内容) - cornbug (0 bytes) 2016-04-29, 16:40:14 (806694)
        
        eletrohydraulically augmented brake applies to bus rather than bike. (无内容) - hopelessless (0 bytes) 2016-04-29, 16:48:21 (806695)
        
        If it is a peddle bike powered by a kid or a girl, Ha, you know the answer (无内容) - cornbug (0 bytes) 2016-04-29, 16:55:25 (806696)
        
        A bike can be a pedal type or motor type.~~ (无内容) - cornbug (0 bytes) 2016-04-29, 19:02:07 (806701)
        
        A bike can be a pedal type or motor type. (无内容) - cornbug (0 bytes) 2016-04-29, 19:00:49 (806700)
        
        Are you saying that bike could have an eletrohydraulically augmented brake? (无内容) - hopelessless (0 bytes) 2016-04-29, 17:00:48 (806698)

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