block with mass M is attached to the end of a massless rigid rod and whirled at a constant speed in a vertical circle with radius R. At the bottom

of the circle,the tension in the rod is equal to three times the weight of the block. What is the speed of the block? \text { O } \sqrt{2 g R} \text { O } \sqrt{3 g R} O_{2} \sqrt{g R} 03 \sqrt{g R}