If R = 12 cm, M = 430 g, and m = 60 g , find the speed of the block after it has descended 50 cm starting from rest. Solve the problem using energy conservation principles. (Treat the pulley as a uniform disk.)

Respuesta :

Answer:

Explanation:

Given

Radius of Pulley r=12 cm

mass of block m=60 gm

mass of Pulley M=430 gm

Block descend h=50 cm

Applying Conservation of Energy

Potential Energy of block convert to rotational Energy of pulley and kinetic energy of block

i.e.

[tex]mgh=\frac{1}{2}I\omega ^2+\frac{1}{2}mv^2[/tex]

where I=moment of inertia

[tex]I=mr^2[/tex]

and for rolling [tex]\omega =\frac{v}{r}[/tex]

[tex]mgh=\frac{1}{2}Mv^2+\frac{1}{2}mv^2[/tex]

[tex]v^2=\frac{2mgh}{m+M}[/tex]

[tex]v=\sqrt{\frac{2mgh}{m+M}}[/tex]

[tex]v=\sqrt{\frac{2\times 60\times 9.8\times 0.5}{430+60}}[/tex]

[tex]v=\sqrt{\frac{60\times 9.8}{490}}[/tex]

[tex]v=\sqrt{1.2}[/tex]

[tex]v=1.095 m/s[/tex]