-->

Units And Measurement

Question
CBSEENPH11020336

A small particle of mass m is projected at an angle θ with the x–axis with an initial velocity v0 in the x–y plane as shown in the figure. At a time t<vosin/g, the angular momentum of the particle is

  • negative mgv subscript straight o space straight t squared space cos space straight theta space bold j with bold hat on top
  • mgv subscript 0 straight t space cos space straight theta space bold k with bold hat on top
  • negative 1 half space mgv subscript 0 straight t squared space cos space straight theta bold space bold k with bold hat on top bold space
  • 1 half space mgv subscript straight o space straight t squared space cos space straight theta space bold i with bold hat on top

Solution

C.

negative 1 half space mgv subscript 0 straight t squared space cos space straight theta bold space bold k with bold hat on top bold space

The angular momentum  of the projectile is given by,
L = m (r x v)
straight L space equals space straight m space left square bracket space straight v subscript 0 space cos space straight theta space straight t space bold i with hat on top space plus space left parenthesis straight v subscript 0 space sin space straight theta space minus space gt right parenthesis bold j with hat on top right square bracket
space space space space space space space space space space space space space straight x space left square bracket space straight v subscript straight o space cos space straight theta space straight t space bold i with hat on top space plus space left parenthesis straight v subscript 0 space sin space straight theta minus space gt right parenthesis bold j with hat on top right square bracket
equals space mv subscript 0 space cos space θt space open square brackets negative 1 half gt close square brackets bold space bold k with bold hat on top
bold space bold equals space minus 1 half space mgv subscript 0 space straight t squared space cos space straight theta bold space bold k with bold hat on top