Afreight train consists of two 8.00×104-kg engines and 45 cars with average masses of 5.50×104 kg . (a) what force must each engine exert backward on the track to accelerate the train at a rate of 5.00×10–2m/s2 if the force of friction is 7.50×105n, assuming the engines exert identical forces?

Explanation:

First of all, let's calculate the total mass of the train+the engines:

Then we can apply Newton's second law, which states that the resultant of the forces is equal to the product between mass (m) and acceleration (a):

(1)

In this case there are two forces:

- The pushing force exerted by the engines, F

- The frictional force, , in an opposite direction to the acceleration

So (1) becomes

Since the acceleration must be

We  can solve the formula to find F:

However, this is the force exerted by both engines. So the force exerted by each engine must be half this value:

as we probably am aware that our atmosphere or air have various levels, each level has different gasses, and each gas has another porousness. at the point when the light originates from lower porousness to higher penetrability, it alters its course. with the goal that implies that when the light originates from the moon to the earth, it alters it's course a lot more occasions. it essentially implies that the state of the light piece of the moon is changed on the earth.

not copied too! hope this !

joke:

h o h o hope you have a merry christmas!