Hi, I 'm Peter. This is the photo of my family. My grandfather is with glasses. He has little hair. The one standing next to him is my father. He is wearing a cap. My grandmother has gray hair. She is a kind woman. She is holding my younger sister. She has short curly hair. The woman standing behind me is my mom. She has straight( 笔直的 ) brown hair. There is a little boy sitting on the table. His name is Paul. He is my brother. He is wearing a green T-shirt and a pair of green socks. It's his favorite color. Which one is my uncle? Well, he is wearing glasses, too. He is in brown shorts and brown shoes. His name is Sam. Now, do you know where he is?

卢瑟福用α粒子轰击氮核发现质子．发现质子的核反应为： ${}_7^{14}$ N+ ${}_2^4$ He→ ${}_8^{17}$ O+ ${}_1^1$ H．已知氮核质量为m_N=14.00753u，氧核的质量为m_O=17.00454u，氦核质量m_He=4.00387u，质子（氢核）质量为m_p=1.00815u．（已知：1uc²=931MeV，结果保留2位有效数字）求：