Solid homogeneous cylinders 400 mm high and 250 mm in diameter are supported by a flat c...

Solid homogeneous cylinders 400 mm high and 250 mm in diameter are supported by a flat conveyor belt which moves horizontally. If the speed of the belt increases according to v = 1.2 + 0.9t² m/s, where t is the time in seconds measured from the instant the increase begins, calculate the value of t for which the cylinders begin to tip over. Cleats on the belt prevent the cylinders from slipping.