« previous next »
Pages: 1 2 3 [4]   Go Down

Author Topic: phys doubt  (Read 5911 times)

Offline Phosu

  • SF Immigrant
  • **
  • Posts: 83
  • Reputation: 97
Re: phys doubt
« Reply #45 on: March 28, 2010, 04:04:01 pm »
A particle is acted upon by two forces F1 and F2 , given by
F1 = (i – 3j) N,
F2 = ( pi + 2pj) N, where p is a positive constant.
(a) Find the angle between F2 and j

how do we find the angle?
Logged

Offline astarmathsandphysics

  • SF Overlord
  • *********
  • Posts: 11271
  • Reputation: 65534
  • Gender: Male
  • Free the exam papers!
Re: phys doubt
« Reply #46 on: March 28, 2010, 04:08:25 pm »
Cos x =u.v/|u||v|
Logged

Offline halosh92

  • SF Senior Citizen
  • *****
  • Posts: 730
  • Reputation: 1113
  • Gender: Female
    • meticulous-me
Re: phys doubt
« Reply #47 on: March 28, 2010, 04:56:54 pm »
Quote from: astarmathsandphysics on March 28, 2010, 04:08:25 pm
Cos x =u.v/|u||v|

could you expalin in  details plz?
Logged
everyday we wake up is a miracle, then how do we say miracles dont happen?????

Offline astarmathsandphysics

  • SF Overlord
  • *********
  • Posts: 11271
  • Reputation: 65534
  • Gender: Male
  • Free the exam papers!
Re: phys doubt
« Reply #48 on: March 28, 2010, 05:19:21 pm »
F1 = (i – 3j) N,
F2 = ( pi + 2pj) N, where p is a positive constant.
F1.F2=1*p+-3*2p=-5p
|F1|=sqrt(1^2+(-3)^2)=sqrt(10)
|F2|=sqrt(p^2+(2p)^2)=sqrt(5p^2)
cos theta=-5p/sqrt(10)sqrt(5p^2)=5over sqrt(50)=1/sqrt(2)
theta=cos^-1 1/sqrt()=45
Logged
Pages: 1 2 3 [4]   Go Up
« previous next »