Solving a problem in physics section 3 point 90 mechani

90. The pendulum in the form of a homogeneous sphere, tightly fastened with a thin rod length l is equal to the radius R of the ball, can swing around a horizontal axis through the end of the rod. The ball is normal to the surface of the bullet hit the mass m = 10 g, flying at a speed V = 800 m / s, and is stuck in the ball. M = mass of the ball 10 kg, its radius R = 15cm. At what angle α deviates pendulum as a result of impact of the bullet? Massa rod neglected.