The block lies on the board. If you raise one end, then at an angle of 30 degrees, the bar

The block lies on the board. If you raise one end, then at an angle of 30 degrees, the bar begins to move. If the angle of inclination of the board with the horizon is 45 degrees, then the bar will slide off the board 1m long in time …

We use the law of conservation of mechanical energy: m * g * h = m * v ^ 2/2

h from a right-angled triangle: h = S * sinα

The formula for the sliding time of a body along an inclined plane, in the case when the friction force can be neglected, looks like this:

t ^ 2 = 2 * h / g * sin ^ 2α

Substitute h: t ^ 2 = 2 * S * sinα / g * sin ^ 2α, reduce by sinα, we get

t ^ 2 = 2 * S / g * sinα, substitute the values, we get:

t ^ 2 = 2 * 1/9, 8 * sin45, t ^ 2 = 0.28, t = 0.5