Question

Falls resulting in hip fractures (or head injuries) are a major cause of injury and even death to the
elderly. Typically, the hip’s speed at impact is about 2.0 meters per second. If this can be reduced
to 1.3 meters per second or less, the hip will usually not fracture. One way to do this is by wearing
elastic hip pads.
(a) If a typical pad is 5.0 centimeters thick and compresses by 2.0 centimeters during the impact of
a fall, what acceleration (in meter per second squared and in g’s) does the hip undergo to reduce
its speed to 1.3 meters per second?
(b) The acceleration you found in part (a) may seem like a rather large acceleration, but to fully
assess its effects on the hip, calculate how long it lasts.

Answer 1

2^2 - 1.3^2 = 2a(.03) (meters). Compare to 9.8.
Use any other equation of motion to find t.