A truck accelerates at a rate of 1 m/s2 for 10 seconds. At that time the truck continues traveling at a constant velocity for the next 20 seconds. The truck then begins to slow down at a rate of -1 m/s2 until it comes to rest. How far did the truck travel for the whole 40 seconds? Please show the equation and substitution for this.

see earlier answer

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.

there are no components of a physical goal mentioned on the list of choices that you've provided.