A body is moving on a circle of radius 80 m with a speed 20 m/s which is decreasing at the rate 5 `ms^(-2)` at an instant. The angle made by its acceleration with its velocity is

Options

A. `1.25m`
B. `12.5m`
C. `25m`
D. `2.5m`

Answer

A

Explanation

`a_(n)=sqrt(a^(2)-a_(t)^(2))=sqrt((100)^(2)=(60)^(2))=80ms^(-2)`
Now, `a_(n)=(v^(2))/(R)"or"R=(v^(2))/(a_(n))=((10)^(2))/(80)=1.25m`