在如此短暂的时间内，所有产生向前推力的机械力必须通过腿来传递。
In that short time, all of the mechanical forces that produce forward propulsion must be transferred through the leg.
这种极性的变化导致列车前方牵引列车前进的电磁场，同时列车后面的电磁场加上了更多的向前推力。
This change in polarity causes the magnetic field in front of the train to pull the vehicle forward, while the magnetic field behind the train adds more forward thrust.
这提供了一个向前的运动，称为推力。
他建议采用电动机或者有形状记忆功能的材料来反复击打软体契形翅膀的末端，让水产生向后的涟漪从而获得向前的推力。
He suggests using electric motors or shape-memory materials to repeatedly flick the end of a flexible, wedge-shaped wing, creating a wave that ripples backwards and generates forward thrust.
该肌腱形似绳索，一头连着小腿的腓肠肌和比目鱼肌，另一头与跟骨相连，在人体行走，跳跃或跑动时，行成向前的推力。
The rope-like tendon connects the calf muscles, the gastrocnemius and the soleus, to the heel bone, and is responsible for pushing off when you walk, jump or run.
最后，支架的推力油缸试图向前推进输送机和为下一次切割做准备。
Finally, the advancing ram of the support in question is extended to push the conveyor forward and becomes ready for the next cut.
直升机旋翼既要提供升力又要提供向前的推力是造成这一情况的主要原因，同时旋翼产生的震动也是一个让直升机飞不能高速飞行的部分原因。
That is partly because of increasing vibration, but mainly because the spinning rotor blades provide both lift and propulsion.
这会产生向前巨大的推力，进而推动你身体连续地向前，而不是上上下下。
What that allows is a huge force forward, allow your body to continuously move forward line, rather than up and down.
这个很有意思，明轮推水或者桨叶方式的推水产生了上举力和向前的推力，在这种情况下上升力和推力会叠加在一起。
Interestingly, the paddle wheel or propeller style movement creates lift and thrust. In this case lift adds to thrust.
虽然与直升机外观相似，但自转旋翼机必须依靠向上流过桨叶地气流维持旋翼地旋转，产生将飞行器维持在空中地升力以及向前飞行地推力。
While similar to a helicopter rotor in appearance, the autogyro's rotor must have air flowing up and through the rotor disk in order to generate rotation.
虽然与直升机外观相似，但自转旋翼机必须依靠向上流过桨叶地气流维持旋翼地旋转，产生将飞行器维持在空中地升力以及向前飞行地推力。
While similar to a helicopter rotor in appearance, the autogyro's rotor must have air flowing up and through the rotor disk in order to generate rotation.
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