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2 months ago

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Vehicle crumple zones are designed to absorb energy during an impact by deforming to reduce energy transfer to the occupants. Ho

w much kinetic energy, in Btu, must a crumple zone absorb to fully protect occupants in a 3000-lbm vehicle that suddenly decelerates from 10 mph to 0 mph?

1 answer:

kicyunya [3.2K]2 months ago

5 0

Answer:

change in KE = -12.95 Btu

Explanation:

provided data

mass = 3000-lbm

initial velocity of vehicle vi = 10 mph = 14ft/s

final velocity of vehicle vf = 0 mph = 0 ft/s

solution

the crumple zone is designed to absorb kinetic energy upon impact

thus the change in KE is related to the initial and final speeds, expressed as:

change in KE = 0.5 × m × (vf² - vi² ).................1

Substituting in the parameters yields:

change in KE = 0.5 × 3000 × (0² - 14.7² )

change in KE = -324135 × $\frac{1lbf}{32.174\ lb.ft/s^2}$ * $\frac{1Btu}{778.17 ft.lbf}$

change in KE = -12.95 Btu

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