1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Lamp tips over and hits the top of the head

  1. Dec 6, 2015 #1
    Imagine a lamp tips over and hitst the top of the head. the lamp weighs about 300 gram and the distance when it started to tip over and hit the head was about 15 centimeters. in the moment of the impact the lamp has tipped over excactly for 90 degrees. The material is Metal that deforms only very little.

    what g force did the impact have?
     
  2. jcsd
  3. Dec 6, 2015 #2

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    It depends crucially on the deformation of the metal and the floor. Absolutely no deformation would lead to "infinite" acceleration, but absolutely no deformation is impossible.
    As rough approximation: (braking distance)/(distance it fell).
     
  4. Dec 6, 2015 #3

    Dale

    Staff: Mentor

    You need to know how fast it was going right before the impact, and how long it took to stop.
     
  5. Dec 6, 2015 #4
    As braking distance I would take 1 millimeter for the deformation of the scalp and 1 millimeter for the deformation of the lamp.

    as falling acceleration we could take 10 m/s (falling acceleration)

    the time it took to stop is hard to estimate
     
  6. Dec 6, 2015 #5

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    10m/s is a speed, the gravitational acceleration in free fall is 10m/s2.
    The lamp is not in free fall, however, as its base always has contact to the floor. It is possible to get a good estimate of its speed (if you know its mass distribution and so on), but I don't think you care about a factor of ~1.5 here, so assuming a free fall gives a reasonable estimate. There is a simple formula to find the speed of an object after falling down a given height. This will also help to find the stopping time.
    Alternatively, you can directly use the approximation I gave in post 2. It assumes uniform deceleration which is probably not true either, but precise values are much more work.
     
  7. Dec 6, 2015 #6

    CWatters

    User Avatar
    Science Advisor
    Homework Helper

    You can estimate the deceleration that the lamp will experience and express that in terms of g, but perhaps you care more about the head?
     
  8. Dec 6, 2015 #7

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member

    Somebody else's!.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Lamp tips over and hits the top of the head
  1. Aquarium Tipping Over? (Replies: 27)

  2. Meter stick tipping over (Replies: 11)

Loading...