1. assume that during each pulse a mammalian heart accelerates 21 g of blood from 18 cm/s to 28 cm/s during a time interval of 0.10 s. calculate the magnitude of the force (in newtons) exerted by the heart muscle on the blood.

2. a 98-kg man on ice skates pushes a 49-kg boy, also on skates, with a force of 100 N. The force exerted by the boy to the man is..?

3. a 12-kg toboggan is pulled along at a constant velocity on a horizontal surface by a horizontal force of 11 N. what is the coefficient of friction?

4. a 10-N force is applied to mass m. the same force is applied to mass 4M. the acceleration of the smaller mass is ____ than the acceleration of the larger mass.

please help, thank you