Which of the following could be cause of a irregular systolic reading 1. The one-way valves are not working
2 Blood is not flowing properly from the veins to the heart
3 Carbon dioxide and oxygen are mixing in the blood
4. The left ventricle is having difficulty contracting

Suppose that three astronomical objects, 1, 2, and 3 are observed to lie on a line, and the distance from object 1 to object 3 is d. object 1 has four times the mass of object 3, and seven times the mass of object 2. find the distance between objects 1 and 2 for which the net force on object 2 is zero.