-- If velocity is constant, then there is no net force
on the chair.
-- If there is no net force on the chair, then friction
must exactly balance out your push.
-- The force of friction is exactly equal in magnitude
to your push, and in exactly the opposite direction.
For this problem, we use the derived equations for rectilinear motion at constant acceleration. The equations used for this problem are:
a = (v - v₀)/t
2ax = v² - v₀²
where
a is the acceleration
x is the distance
v is the final velocity
v₀ is the initial velocity
t is the time
The solution is as follows;
a = (60mph - 30 mph)/(3 s * 1 h/3600 s)
a = 36,000 mph²
2(36,000 mph²)(x) = 60² - 30²
Solving for x,
x = 0.0375 miles
Answer:

Explanation:
As the path is straight, so the speed is equivalent to velocity. Now. assuming that the acceleration and deceleration of the train are constant. So, change of velocity with respect to time for acceleration as well as deceleration is constant. Hence, the slope of the speed-time graph is constant for the time of acceleration as well as deceleration. The speed for the time from
to
is constant, so slope for this interval of time is zero. The speed-time graph is shown in the figure.
The total distance covered by the train during the entire journey is the area of the speed-time graph.
Area


As velocity is in
and time is in
so the unit of area is 
Hence, the total distance is
.
The seafloor is only expanding in one area, which is the Atlantic Ocean. It's just Earth's seafloor recylcing itself.