A 0.25 ball is thrown with the speed of v=4.5m/s at a resting stick that can rotate around one end at the axis O. The ball hits the stick at r=0.75 m from O. What is the angular momentum of the ball about the axis O before hitting the stick ?

Respuesta :

Answer:

[tex]\mathbf{^\to Q =0.84375 \ (- \hat z) \ kgm^2s^{-1}}[/tex]

Explanation:

mass of the ball = 0.25  kg

its speed v = 4.5 m/s  

r = 0.75 m

let the speed be in the horizontal direction and the distance r be in the vertical direction we have :

[tex]^ {\to}v = 4.5 \ x \ \ m/s[/tex]

[tex]^ {\to}r = 0.75 \ y \ \ m/s[/tex]

Let the momentum about the center of intersection be P;

SO;

[tex]^ \to} P = ^{\to} mv[/tex]

[tex]^ \to} P = 0.25* 4.5 \ x \ \ m/s[/tex]

[tex]^ \to} P = 1.125 \ x \ \ m/s[/tex]

Let the angular momentum be Q;

[tex]^\to Q = ^ \to r* ^ \to P[/tex]

[tex]^\to Q = (0.75*1.125) kgm^2s^{-1} *(\hat y * \hat x)[/tex]

[tex]\mathbf{^\to Q =0.84375 \ (- \hat z) \ kgm^2s^{-1}}[/tex]

Answer:

-0.84

Explanation:

If you multiply 0.25 by 4 you get 1.

it's negative because of the mass so -1.

- 1 + 0.16 = -0.84