A block takes t time to slide down a plane inclined at 45° to the horizontal. If the surface is made smooth (frictionless), the block takes time t/2…

A block takes $\displaystyle t$ time to slide down a plane inclined at $\displaystyle 45$° to the horizontal. If the surface is made smooth (frictionless), the block takes time $\displaystyle \frac{t}{2}$ to slide down the plane. The coefficient of friction between the block and the inclined plane is $\displaystyle \left(\frac{\alpha}{100}\right)$. The value of $\displaystyle \alpha$ is $\displaystyle \_\_\_\_$.