Answer:
The horse is going at 12.72 m/s speed.
Step-by-step explanation:
The initial speed of the horse (u) = 3 m/s
The acceleration of the horse (a)= 5 m/
![s^(2)](https://img.qammunity.org/2020/formulas/physics/middle-school/6tzd9jx3jcbjv5zphhkqd2l52b24mrknt6.png)
The displacement( it is assumed it is moving in a straight line)(s)= 15.3 m
Applying the second equation of motion to find out the time,
![s=ut+(1)/(2)at^(2)](https://img.qammunity.org/2020/formulas/physics/middle-school/9j4x6xrk6gvzni2wbx2t7rnnebjctnuk4a.png)
![15.3=3t+2.5t^(2)](https://img.qammunity.org/2020/formulas/physics/college/4jef6fk7pbid6kyzyvtgqo0xtfurv2o05t.png)
![2.5t^(2)+3t-15.3=0](https://img.qammunity.org/2020/formulas/physics/college/58kmhbz0rthxbt4u55wmrw6xnum7u3b8lz.png)
Solving this quadratic equation, we get time(t)=1.945 s, the other negative time is neglected.
Now applying first equation of motion, to find out the final velocity,
![v=u+at](https://img.qammunity.org/2020/formulas/physics/middle-school/8u69t2dm31jy4f6e8h3i9msisjzkrvuvq4.png)
![v=3+1.945*5](https://img.qammunity.org/2020/formulas/physics/college/e28k5z7uqbas9qxibfc2fqfa70bodnrxas.png)
![v=3+9.72](https://img.qammunity.org/2020/formulas/physics/college/vgqw0nsufujwon09d6njc7w44dg3ftvkmy.png)
v=12.72 m/s
The horse travels at a speed of 12.72 m/s after covering the given distance.