弹道学：关于射弹动力学的研究。

Ballistics: the study of the dynamics of projectiles.

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振动频率对回弹动弹模有一定影响，高振频使测定值有所下降。

Vibratory frequency has some effect on measured value of the unloaded dynamic elastic modulus. Higher vibratory frequency may decrease a little the value of the modulus.

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一只卡在蜘蛛丝上，弹动不得的小白蜢，像是走在钢索上，形成了这可爱的画面。

A white little hopper stuck on the spider web, looks like a Tightrope Walker, very funny indeed.

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