<div class=\"column\"> <p><span>In a script for a movie scene, a bridge is remot

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<p><span>In a script for a movie scene, a bridge is remotely detonated by explosives as the hero races towards it in her car. After the detonation, she brakes the car as hard as possible, but realizes that the car won't be able stop in time and jumps out just before it shoots off the edge of the bombed bridge. </span></p>
<p><span>Obviously, the faster the car is going before it begins braking, the more exciting the scene, so the director wants an initial speed of 90 mph (40 m/s). The stunt coordinator says that the driver will be safe if the car is going no more than 25 mph (11 m/s) when she jumps out. To set up the shot as the director wishes, the car can't begin braking until it's 80 m from the edge of the bridge (where the edge will be after the explosives go off). </span></p>
<p><span>The coefficient of kinetic friction between the car's tires and the road surface is known to be 0.78, and wind tunnel tests on the car have established that the it will be subject to an average air resistance force of no more than 3500 N when slowing down. </span></p>
<p><span>Can the stunt be pulled off as the director and stunt coordinator want, or will the plan have to be changed? Choose a reasonable mass for the car to use in your calculations.&#160;</span></p>
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Explanation / Answer

taking mass of car = 500kg now frictional force = 500*g*.78 = 3900 total force = 3500+3900=7400 deceleration = 7400/500 = 14.8m/s now checking what distance car would stop aftr breaking v^2=50^2 - 2*14.8*80 v=11.4 it is not saafe since velocity is greator than 11m/s

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