1. Not finding help here? Sign up for a free 30min 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!

Instaneous power delivered by the force at any timet

  1. Oct 16, 2004 #1
    A force F acts on a particle of mass m. The particle starts from rest at t=0.
    a) show that the instaneous power delivered by the force at any timet is (F^2/m)*t
    Please give some directions how to solve it . Thank you
  2. jcsd
  3. Oct 16, 2004 #2
    Any idea where to start? (hint: what is the formula for power)
  4. Oct 16, 2004 #3
    formula P=W/t or P=FV , and I don't know how to get t and and m involve in the formula
  5. Oct 17, 2004 #4
    Think of the definition of velocity. [tex]v = a t[/tex]. And then use Newton's Seond Law for [tex]a[/tex].
  6. Oct 17, 2004 #5
    Thank you very much, I got it, and I have another homework.
    A raindrop (m=3.35*10^-5 kg) falls vertically at a constant speed under the influence of gravity and air resistance. after the drop has fallen 100m,
    a)what is the work done by gravity?
    b)the energy discipated by air resistance?
    I got no clue for air resistance . Thank you
  7. Oct 17, 2004 #6
    If the raindrop where in the vacuum, the falling speed will not be constant. But when we do the experiment in a fluid, then a viscosity force appears and makes the raindrop or something else reach a constant speed. This force is proportional to the speed, so you may use newtonian physics...
  8. Oct 17, 2004 #7
    is it called resistive force?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Instaneous power delivered by the force at any timet