Asked by john
In coming to a stop a car leaves skid marks 92m long on the highway. Assuming a decceleration of 7.00m/s^2, estimate the speed of the car just before braking.
Answers
Answered by
Henry
d = 0.5 * a * t^2,
92 m = 0.5 * 7.0 m/s^2 t^2,
92 = 3.5t^2,
t^2 = 92/3.5 = 26.29,
t = sqrt(26.29) = 5.13 s.
a = (Vt - Vo) / t,
-7.00 m/s^2 = (0 - Vo) / 5.13 s,
-7.00 = -Vo /5.13,
-Vo = - 7.0 * 5.13 = -35.91,
Vo = 35.91 m/s. = velocity Just before braking.
92 m = 0.5 * 7.0 m/s^2 t^2,
92 = 3.5t^2,
t^2 = 92/3.5 = 26.29,
t = sqrt(26.29) = 5.13 s.
a = (Vt - Vo) / t,
-7.00 m/s^2 = (0 - Vo) / 5.13 s,
-7.00 = -Vo /5.13,
-Vo = - 7.0 * 5.13 = -35.91,
Vo = 35.91 m/s. = velocity Just before braking.
Answered by
Erin
Where did you get the 0.5?
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