A driver involved in an accident claims he was going only 25mi/h. When police tested his car,they found that when the brakes were applied at 25mi/h, the car skidded only 45ft before coming to a stop. The driver's skid marks at the accident scene measured 210ft. Assuming the same (constant) deceleration, calculate the speed at which he was traveling prior to the accident.
answer: around 54 mi/h
Maths Pls help
2013-11-12 5:09 am
回答 (1)
2013-11-12 6:24 am
✔ 最佳答案
From Physics v² = u² - 2aSLet v = 0 ; the car stop finally
u² = 2aS
let it be
u² = kS
Put u = 25 and S = 45
k = 13.89
u² = (13.89)(210)
u = 54
2013-11-11 22:44:45 補充：
如果這條是 physics 而不是 maths.
將 1 mile = 1760 yard
1 yard = 3 feet 去化 1 mile = 5280 ft 再做會更正路一點。
收錄日期: 2021-04-27 20:34:23
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https://hk.answers.yahoo.com/question/index?qid=20131111000051KK00220