If the it took the object travelling at 25m/s 1 second to travel a quarter of the circle, it means a quarter of the circle is 25m (it travels 25m in one second).
If the quarter of the circle is 25m than the circumference of the circle is 100m.
We want to calculate the radius of the circle.
Remember that the equation for finding the circumference contains the radius. We can use that equation to solve for the radius.
Circumference = 2πr
π = pi or 3.1415...... ( a number )
r = radius
Since we know the circumference, plug it in.
100m = 2πr
solve for the radius by isolating r.
100m/2π = r
r = radius = 100m/2π = 50m/π = 50/π meters
Answer: Radius = 50/π meters