Solution:

v = u+at

v = 0+20 (It Starts From Rest)

v = 20m/s

1) Answer- 20m/s

a = v-u/t

a = 0-20/20

a = -1m/s^2

2) Answer- -1m/s^2

Distance = Speed*Time

1st Case= 25*900 = 22500m

Or 22.5 Km

Now 2nd Case

s = ut+1/2at^2

s = 25*20+1/2(-1*20*20)

s = 500-200

Or 300 m

Total Distance = 22500+300 = 22800m

But We Are Forgetting One Thing

It Started From Rest It Attained Its Maximum Speed in 10 seconds so it should cover some distance in that period

s = ut+1/2at^2

s = 0+1/2*2*10*10

s = 100m

Total Distance = 22800+100 = 22900m Or 22.9 Km

A train starts its journey from station P:

When a train starts its journey from station P, it undergoes various motions and experiences different physical phenomena. Let's discuss these motions and phenomena in detail.

1. Rectilinear Motion:
The train initially moves in a straight line, known as rectilinear motion. This motion occurs when the train travels along a straight track without any change in direction. The train's speed and acceleration determine its motion during this phase.

2. Uniform Motion:
If the train maintains a constant speed during its journey, it is said to be in uniform motion. In this case, the train covers equal distances in equal intervals of time. The velocity of the train remains constant, and there is no acceleration.

3. Non-uniform Motion:
If the train changes its speed or direction during its journey, it is said to be in non-uniform motion. This can occur due to various factors like acceleration, deceleration, or changes in the track's curvature. Non-uniform motion can be mathematically described using equations of motion.

4. Acceleration:
Acceleration is the rate at which the train's velocity changes with time. If the train's speed increases, it experiences positive acceleration, while a decrease in speed results in negative acceleration. The train's acceleration can be calculated using the equation a = (v - u) / t, where 'a' is acceleration, 'v' is final velocity, 'u' is initial velocity, and 't' is the time taken.

5. Friction:
Friction plays a significant role in the train's motion. It opposes the train's motion and acts between the wheels and the track. Friction helps the train to maintain its grip on the track, preventing it from slipping or skidding. It also aids in stopping the train by providing a braking force.

6. Newton's Laws of Motion:
The train's motion is governed by Newton's laws of motion. Newton's first law states that an object will remain in its state of motion unless acted upon by an external force. This law explains the train's tendency to continue moving in a straight line unless acted upon by external forces like friction or air resistance.

7. Energy Conservation:
During the train's journey, energy is continuously being converted from one form to another. The train's engine converts chemical energy into mechanical energy, which is then used to overcome friction and move the train. The train's kinetic energy is also changed during acceleration or deceleration.

8. Momentum:
The train also possesses momentum, which is the product of its mass and velocity. Momentum is conserved in an isolated system, and any change in the train's momentum is due to external forces acting on it.

In conclusion, when a train starts its journey from station P, it undergoes rectilinear or non-uniform motion, experiences acceleration, encounters friction, follows Newton's laws of motion, and undergoes various energy conversions. Understanding these concepts helps us analyze and describe the train's motion accurately.