I need help with two question

What is the volume of a rectangular prism if the length is 10.4 mm the width is 5 mm in the height is 8 mm

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

After t seconds, a ball tossed in the air from the ground level reaches a height of h feet given by the equation h = 144t-16t^2. after how many seconds will the ball hit the ground before rebounding?