Answer:
change in KE = -12.95 Btu
Explanation:
given data
mass = 3000-lbm
velocity of vehicle initial vi = 10 mph = 14ft/s
velocity of vehicle final vf = 0 mph = 0 ft/s
solution
as here for crumple zone to protected zone it will absorb kinetic energy
so change in KE is related here initial and final velocity that is
change in KE = 0.5 × m × (vf² - vi² ) .................1
put here value and we get
change in KE = 0.5 × 3000 × (0² - 14.7² )
change in KE = -324135 × *
change in KE = -12.95 Btu