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This effect is explained by increased chain entanglements at higher molecular weights. Increasing the degree of crystallinity of a semicrystalline polymer leads to an enhancement of the tensile strength. Deformation by drawing increases the tensile strength of a semicrystalline polymer.
Here we can say that rate of flow must be constant
so here we will have

now we know that


now from above equation



so velocity will reduce by factor 0.14
Half mass car because it's traveling faster