4-13. Two wheels are welded together and they turn at the same rate. The double wheel has a total mass of and a radius of gyration . The radiuses of the two wheels are and , respectively. A normally distributed force is applied to the inner wheel to hoist the 45 kg block that is attached to the outer wheel. If the block is originally at rest and the mass of the rope is negligible, determine the probability that the velocity of the block is smaller than 10 m/s after 2 seconds.