Scientists and engineers must interpret problems from various sources. We can pr

Question

Scientists and engineers must interpret problems from various sources. We can practice this skill anytime we read a newspaper or magazine or browse the Internet. Consider the "Rocket Car" urban legend that can be found on many Internet sites, in which the Arizona Highway Patrol allegedly found the vaporized wreckage of an automobile. The story goes that after some analysis and investigation, it was believed that a former Air Force sergeant attached solid-fuel rockets to his 1967 Chevy Impala and ignited the rockets approximately 5.7 miles from the crash site. The vehicle quickly reached a speed of approximately 282 mph. It continued at this speed for 25 seconds. The car remained on the highway for 2.5 miles before the driver applied the brakes. The brakes melted and the tires blew out, causing the vehicle to become airborne. It traveled through the air for 3.2 miles before it hit a cliff face 185 feet above the road. Of course, this story was debunked. It is physically implausible, but it can still provide an opportunity to practice analyzing a problem.

For the constant-velocity part of the car's motion, calculate the displacement using the position data and then again using the velocity and time data. (Enter the magnitudes only.)

a) displacement using the position data _______m

b) displacement using the velocity and time data ______m

Explanation / Answer

This is a time Velocity problem

The car was initially 5.7 miles away from crash site, where it was ignited and the car moved for 2.5 miles before brakes were applied. Then the car flew for 3.2 miles before hitting a cliff 185 feet.

Position of car before brakes were applied

a) It had travelled for 2.5 miles till it's Velocity was constant which 2.5 *1609.344 = 4023.36 m. As the brakes were applied the Velocity had changed.

b) Using Velocity time data,

displacement = Velocity * time

displacement = 282 mph * 25 s = 126.054 m/s * 25 s

displacement = 3151.35 m

The collision with cliff has not been considered as the Velocity was not constant due to application of brakes.

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