Question

A 0.70-kg disk with a rotational inertia given by MR 2/2 is free to rotate on a fixed horizontal axis suspended from the ceiling. A string is wrapped around the disk and a 2.0-kg mass hangs from the free end. If the string does not slip then as the mass falls and the cylinder rotates the suspension holding the cylinder pulls up on the mass with a force of______

Answer 1

Answer:

The force will be "9.8 N".

Explanation:

The given values are:

mass,

m = 0.7 kg

M = 2

g = 9.8

Now,

⇒  $\tau = T \alpha$

then,

⇒  $\frac{1}{2}mR^2(\frac{1}{R}\frac{dv}{dt}) =M(g-a_t)R$

⇒  $\frac{1}{2}m \ a_t=m(g-a_t)$

⇒  $a_t=\frac{2g}{(\frac{m}{M} +2)}$

On substituting the values, we get

⇒      $=\frac{2\times 9.8}{\frac{0.7}{2} +2}$

⇒      $=8.34 \ m/s$

hence,

⇒  $T=mg+M(g-a_t)$

On substituting the values, we get

⇒      $=0.7\times 9.8+2(9.8-8.34)$

⇒      $=6.86+2(1.46)$

⇒      $=6.86+2.92$

⇒      $=9.8 \ N$