Your question wants to know how much it turns in 1 turn. That means it wants to know the circumference.
The circumference formula is as follows:
[tex]\sf{C= 2\pi r}[/tex]
The diameter is 50 cm, that means the r or radius is 25 cm.
So plugging that into the formula we get:
[tex]\sf{C=2 \times 25 \times \pi}[/tex]
Simplifying that, we get your final answer as
[tex]\huge{\boxed{\bf{50 \pi = 157.08m}}}[/tex]
