Answer:
The horse's final speed is 8.31 m/s
Step-by-step explanation:
Motion With Constant Acceleration
It's a type of motion in which the velocity of an object changes uniformly in time.
The equation that describes the change of velocities is:
![v_f=v_o+at\qquad\qquad [1]](https://img.qammunity.org/2022/formulas/physics/high-school/zqckt89rlb2v0qgonskyi9dd240h8tlbek.png)
Where:
a = acceleration
vo = initial speed
vf = final speed
t = time
The distance traveled by the object is calculated as follows:
![\displaystyle x=v_o.t+(a.t^2)/(2)\qquad\qquad [2]](https://img.qammunity.org/2022/formulas/physics/high-school/zh283gv9qnf95esv02n7ge67bq5asru6vj.png)
Solving [1] for t and substituting into [2] we get the following equation:

Now we use the data provided by the question. The horse starts at vo=3 m/s and then accelerates at
for a distance of x=15 m. The final speed is:




The horse's final speed is 8.31 m/s