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单选题
难度系数:

1.一根劲度系数是的弹簧原长是,当它的长度变为时,弹簧的弹力大小是 ,若使弹簧的长度再增加,对弹簧施加的拉力需增大.
A: 2N,2N
B: 2N,4N
C: 4N,2N
D: 4N,4N
  • 提示1IOeUseiDoeWFi+WumuW+i+WPr+efpe+8jOW8ueewp+eahOW8ueWKmzxpbWcgd2lkdGg9MjgwIGhlaWdodD0yMyBzcmM9Imh0dHBzOi8vcDEucWluZ2d1by5jb20vRzEvTTAwLzk3L0I1L3JCQUNFMU9UTVR1Umo1amhBQUFFckh0a214ZzUxNi5wbmciPg==
  • 提示2IOS9v+W8ueewp+WGjeS8uOmVvzxpbWcgd2lkdGg9MzAgaGVpZ2h0PTE5IHNyYz0iaHR0cHM6Ly9wMi5xaW5nZ3VvLmNvbS9HMS9NMDAvNUIvQTkvckJBQ0ZGT1RNVHVRUDZObUFBQUJlU282a0VVODU1LnBuZyI+77yM6ZyA5aKe5Yqg55qE5ouJ5YqbPGltZyB3aWR0aD0xOTEgaGVpZ2h0PTIxIHNyYz0iaHR0cHM6Ly9wMS5xaW5nZ3VvLmNvbS9HMS9NMDAvNUIvQTkvckJBQ0ZGT1RNVHZpWGxzN0FBQUQ1eGlhSGxNMjgzLnBuZyI+