Step 1:

\

A small mass m attached to the end of a string revolves in a circle on a frictionless tabletop. The other end of the string passes through a hole in the table (the figure (Figure 1) ). Initially, the mass revolves with a speed v1 = 2.3 m/s in a circle of radius r1 = 0.80 m. The string is then pulled slowly through the hole so that the radius is reduced to r2 = 0.48 m.

\

A small mass $\"\"$ attached to the end of a string revolves in a circle on a frictionless tabletop.

\

The other end of the string passes through a hole in the table.

\

Initially, the mass revolves with a speed $\"\"$ in a circle of radius is $\"\"$ .

\

The string is then pulled slowly through the hole so that the radius is reduced to $\"\"$ .

\

Find the speed $\"\"$ .

\

Initially the angular momentum is $\"\"$ .

\

The angular momentum after reduced the radius is $\"\"$ .

\

The angular momentum is $\"\"$ .

\

Substitute $\"\"$ and $\"\"$ .

\

$\"\"$

\

$\"\"$ .

\

Using law of conservative of angular momentum: $\"\"$ .

\

Therefore, $\"\"$ .

\

The mass $\"\"$ is constant.

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

Substitute $\"\"$ , $\"\"$ and $\"\"$ .

\

$\"\"$

\

$\"\"$

\

$\"\"$ .

\

\

$\"\"$ .

\

\ \

\

\

\

\

\