In coming to a stop, a car leaves skid marks 62 m long on the highway.Assuming a deceleration of 4.30 m/s2 , estimate the speed of the car just before braking.
vf^2=vi^2+2ad
0=vi^2+2(-4.3)(62)
solve for vi
In coming to a stop, a car leaves skid marks 85 m long on the highway. Assuming a deceleration of 4.00 m/s2, estimate the speed of the car just before braking
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To estimate the speed of the car just before braking, we can use the kinematic equation:
v² = u² + 2as
Where:
v = final velocity (which is 0 m/s, as the car comes to a stop)
u = initial velocity (the speed of the car before braking)
a = acceleration (the deceleration in this case)
s = distance (the length of the skid marks)
Rearranging the equation to solve for u, we have:
u² = v² - 2as
Substituting the given values:
u² = 0² - 2 * 4.30 m/s² * 62 m
u² = - 1764.4 m²/s²
Since the square of the speed cannot be negative, we can conclude that the speed of the car before braking is imaginary. This means that something might be incorrect with the given information or the assumption of deceleration. Double-checking the values or clarifying the scenario is recommended.