Afootball is kicked into the air at an angle of 45 degrees with the horizontal. at the very top of the ball's path, the net force acting upon it is (neglect the effects of air resistance.)

Vertical Force Only

Explanation:

When a football or any other particle is thrown at an certain angle then at highest point force acting on it is equal to the weight of object because no other force is acting in the vertical direction except gravity(Neglecting  air resistance).

As long as there is no Force in Horizontal direction there will only be vertical force acting on the football at highest Point          

dicrrdirrkdirckrrdrrk ; jhgfdsgrthyjkul; i'lkjhgfdskhjl; jhgdfs

conservation of mass

mass before something happens = mass afterwards