如图所示,为一轻质弹簧的长度$L$和弹力$F$的关系图线,根据图线可以判断,下列说法中不正确的是( )
A.当弹力$F = 0$时,弹簧处于原长状态,由图知,弹簧的原长$L_0 = 10\text{cm}$,故A正确;
BD.由图看出,当弹簧的长度为$5\text{cm}$时,弹力为$10\text{N}$,此时弹簧压缩量$x = 10\text{cm} - 5\text{cm} = 5\text{cm} = 0.05\text{m}$,根据胡克定律$F = kx$得,$k = \frac {F}{k} = \frac {{10}}{{0.05}} = 200\text{N}/\text{m}$.故BD正确;
C.当弹簧伸长量$x^{\prime} = 15\text{cm} = 0.15\text{m}$,根据胡克定律得,$F = kx^{\prime} = 200 \times 0.15\text{N} = 30\text{N}$.故C错误.
故选C.