00:01
There's a free train that has a given mass of this value and the locomotive can exert a constant pull force of this much newtons.
00:08
So how long will it take for this for it to increase the speed from rest to 80 kilometer per hour? all right.
00:14
So for that force, we need to find the acceleration.
00:18
So the acceleration, we know that is force over mass.
00:21
And the force is 7 .5 times 10 raise to 5 over 10 raise to 5 over the mass, which is, 1 .5 times 10 raised to 7.
00:32
So this comes out as 5 times 10 raised to minus 2 meter per second square.
00:38
This is the required value of the acceleration.
00:40
Now, we will use the equation of motion that v is equal to v0 plus 80.
00:48
This is the first equation of motion.
00:50
And the final speed which they want is 80, but that is in kilometer per hour.
00:56
So we have to convert into it into meter per second.
00:58
So we know that 80 kilometer per hour, 80 kilometer per hour will be equal to 80 times 1000 over 3600.
01:12
So these zeros are canceled...