[填空题]
According to a simplified mode ujf7h*b0p6oqkkwoum(0 e1 sz 49e-nel of a mammalian heart, at each pulsee41u:59 f jcsjcc qg6,ccd7 jz approximately 20 g of bloj4cqs 6jugd5:zfeccc1 c7 ,9jod is accelerated from 0.25 $\mathrm{~m} / \mathrm{s}$ to 0.35 $\mathrm{~m} / \mathrm{s}$ during a period of 0.10 s . What is the magnitude of the force exerted by the heart muscle?
