Label distance between AB, BC and CD. The choices are :
Constant acceleration.
Decreasing acceleration.
Increasing acceleration.
Moving backwards at constant speed.
Moving forward at constant speed.
Stationary.

AB: decreasing acceleration

BC: constant acceleration

CD: constant acceleration.

Explanation:

(1) Here is the plot of velocity and time.

There is no information of distance.

=>  There are two options that will be eliminated.

Moving backwards at constant speed.

Moving forward at constant speed.

(2) Only for remaining options will be considered:

Constant acceleration.

Decreasing acceleration.

Increasing acceleration.

Stationary.

(3) The formula for calculating final velocity:

v_final = v_initial + acceleration x time

Let's see BC: (this is a segment straight line)

v_C = v_B + acceleration x time

v_C = v _B = 40 (km/h)

time > 0

=> acceleration a = 0 (km/h^2) => constant acceleration

Let's see CD: (this is also a segment straight line)

v_D = v_C + acceleration x time

v_D = 0 (km/h)

v_C = 40 (km/h)

time > 0

=> acceleration = -40/time (km/h^2) < 0 => constant (negative) acceleration

Let's see AB (a segment straight line + a right curve)

On the segment straight line:

Using the same way we considered CD,

the acceleration is constant (positive) acceleration

On the right curve (with direction from A to B), its slope started to decrease. This slope is the change of acceleration.

=> Generally on AB (considering both segment straight line and the right curve), the acceleration is decreasing acceleration

P.S: Take the derivative of v_final with respect to acceleration a, plot a as a function of time , then you will see what really happened ^^.

Hope this helps!

the independent variable, or the one that is intentionally manipulated is the speed.

the temperature and the pressure affect solubility. temperature affects by changing the properties of the solvent. the increase in pressure increases solubility, the decrease in pressure decreases solubility.