Physics

posted by .

Pith Balls


Two small pith balls, each of mass m = 17.7 g, are suspended from the ceiling of the physics lab by 0.8 m long fine strings and are not moving. If the angle which each string makes with the vertical is è = 42.6°, and the charges on the two balls are equal, what is the magnitude of that charge (in µC)? (Please note that the unit of charge is micro-Coulomb here - some browsers might not display the Greek letter mu correctly and show it as an m.)

  • Physics -

    If the charged ball is suspended be the string which is deflected by the angle α, the forces acting on it are: mg (downwards), tension T (along the string - to the pivot point), and F (electric force –along the line connecting the charges).
    Projections on the horizontal and vertical axes are:
    x: T•sin α = F, ….(1)
    y: T•cosα = mg. ….(2)
    Divide (1) by (2):
    T•sin α/ T•cosα = F/mg,
    tan α = F/mg.

    Since
    q1=q2=q.
    r=2•L•sinα,
    k=9•10^9 N•m²/C²
    F =k•q1•q2/r² = k•q²/(2•L•sinα)².

    tan α = F/mg =
    = k•q²/(2•L•sinα)² •mg.
    q = (2•L•sinα) • sqrt(m•g•tanα/k)=
    =(2•0.8•sin42.6) •sqrt(0.0177•9.8•tan42.6/9•10^9) =...

  • Physics -

    sqrt((0.0177(2*0.8*sin42.6))(tan42.6)/9*10^9)

  • Physics -

    sqrt((0.0177(2*0.8*sin42.6))(tan42.6)/9*10^9)=1.5*10^-6

  • Physics -

    From what height can a 1-kg falling object cause fracture of the skull? Assume that the object is hard, that the area of contact with the skull is 1 cm2, and that the duration of impact is 10−3 sec.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Science, Physics

    The Pith balls may be positive, negative or neutral. Four pith balls are suspended by insulated threads. The following reaction occurs. a) #2 pith ball is positively charged b) #2 attracts all the other pith balls,. c) #1 and#3 pith …
  2. Physics - Charge on pith balls

    Two pith balls equally charged and each with a mass of 1.5. White one ball is suspended by a thread, the other is brought close to it and a state of equilibrium is reached. In that situation, the two balls are separated by 2.6cm and …
  3. physics

    Two small pith balls, each of mass m = 11.2 g, are suspended from the ceiling of the physics lab by 1.7 m long fine strings and are not moving. If the angle which each string makes with the vertical is è = 30.4°, and the charges …
  4. physics

    Two small pith balls, each of mass m = 11.2 g, are suspended from the ceiling of the physics lab by 1.7 m long fine strings and are not moving. If the angle which each string makes with the vertical is è = 30.4°, and the charges …
  5. Physics Please HELP!!!!!!!!!

    Two small pith balls, each of mass m = 11.2 g, are suspended from the ceiling of the physics lab by 1.7 m long fine strings and are not moving. If the angle which each string makes with the vertical is è = 30.4°, and the charges …
  6. physics

    Two small pith balls, each of mass m = 16.6 g, are suspended from the ceiling of the physics lab by 1.8 m long fine strings and are not moving. If the angle which each string makes with the vertical is è = 19°, and the charges on …
  7. Physics

    Two small pith balls, each of mass m = 10.1 g, are suspended from the ceiling of the physics lab by 0.8 m long fine strings and are not moving. If the angle which each string makes with the vertical is è = 42.1°, and the charges …
  8. Physics

    Two small pith balls, each of mass m = 16.6 g, are suspended from the ceiling of the physics lab by 1.8 m long fine strings and are not moving. If the angle which each string makes with the vertical is è = 19°, and the charges on …
  9. Physics, Electricity and Magnetism, Sciences

    Two small pith balls, each of mass m = 17.4 g, are suspended from the ceiling of the physics lab by 1.2 m long fine strings and are not moving. If the angle which each string makes with the vertical is = 17.9°, and the charges on …
  10. Physics

    Two small pith balls, each of mass m = 17.4 g, are suspended from the ceiling of the physics lab by 1.2 m long fine strings and are not moving. If the angle which each string makes with the vertical is = 17.9°, and the charges on …

More Similar Questions