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

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol  

b. a hockey puck sliding across the ice  

c. a compressed spring  

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice   is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice   is the correct option.