Atrain moving west with an initial velocity of 20 m/s accelerates at 4 m/s2 for 10 seconds. during this time, the train moves a
distance of
meters.

400m

Explanation:

In theory and for a train with an initial velocity the expression reads

Eq. (1): Velocity = Initial Velocity + Acceleration*Time <=> v = v0 + at

We also know that the distance expression for a train with a initial velocity that then accelerates reads

Eq. (2): Distance = 0.5*( Velocity + Initial Velocity )*Time <=> d = 0.5*(v0 +v)*t

Now subsituting in Eq. (1) for all known value we can obtain the Velocity after the acceleration of the train as such:

v = 20 + (4 * 10) <=>

v = 20 + 40 <=>

v = 60m/s

Then plugging in the value for v above, in Eq. (2) we get:

d = 0.5*(20 +60)*10 <=>

d = 0.5*(80)*10 <=>

d = 400m

b.

explanation: