2014 is the year of horse in China. Do you know anything about the horse?

    The horse is strong and runs very fast. He's a useful and hard-working animal. The horse learns to know his owner soon. He loves his owner, even after his owner loses his life. Here's a story about such a horse. In a war, the owner passed away(死), and fell from his horse. When people found his body some days later, the horse was still standing beside it. During that long time, the horse didn't leave the body of his owner, without food or water, in the coldest weather, driving away the birds that might eat it. Wasn't he a great animal?

如图，电动机M的线圈电阻为0.5欧，当S断开时，电流表读数1安，当S闭合时，电流表读数3安。问：

（1）电阻R为多大？

（2）电动机的机械功率为多大？

（3）电动机工作2分钟，电动机线圈产生了多少热量？