Free Fall Acceleration fractures Problem

[tater08]

Homework Statement

Falls resulting in hip fractures are a major cause of injury and even death to the elderly. Typically, the hip’s speed at impact is about 2.0 m/s. If this can be reduced to 1.3 m/s or less, the hip will usually not fracture. One way to do this is by wearing elastic hip pads.

If a typical pad is 5.0 cm thick and compresses by 2.0 cm during the impact of a fall, what acceleration (in m/s^2) does the hip undergo to reduce its speed to 1.3 m/s?

Homework Equations

(y1-y0)=(Vf^2-V0^2)/2a

The Attempt at a Solution

y1-yO=-2 cm = 0.02M Vf= 1.3 V0=2.0 a=?
1.3^2-2.0^2 =-2.31

(-2.31m^2/s^2)/ 2*-0.02m =a a= 57.75m/s^2

question is...did i do this problem right because this is an online homework problem and i keep getting it wrong so I'm wondering if it is the program or if it just me.

thanks

 

[tiny-tim]

Typically, the hip’s speed at impact is about 2.0 m/s. If this can be reduced to 1.3 m/s or less, the hip will usually not fracture. One way to do this is by wearing elastic hip pads.

If a typical pad is 5.0 cm thick and compresses by 2.0 cm during the impact of a fall, what acceleration (in m/s^2) does the hip undergo to reduce its speed to 1.3 m/s?

Hi tater08!

Your answer looks fine to me!

I think it must be a misprint …

hmm … try using 3.0 cm instead of 2.0 cm, and see if the computer accepts that!

 

[baba89]

for your help

Your solution appears to be correct. However, it is always a good idea to double check your calculations and make sure all units are consistent. It is also possible that the online homework program is not accepting your answer due to rounding or other formatting errors. If you continue to have trouble, it may be helpful to reach out to your instructor for clarification or assistance.