00:01
In this question, we have a 12 .6 kilogram object with the speed of 0 .87c.
00:06
We want to calculate the magnitude of its momentum, and if a constant force of 426 neutrons acts opposite to the motion, how long it would take to bring the body to rest.
00:17
So first we start calculating the momentum.
00:20
We know the momentum is equal to the lorentz factor, multiplied by the mass, multiplied by the velocity, where the lorentz factor is given by 1 over the square root of 1 minus, b squared over c squared.
00:32
And we've been told the velocity is 0 .87c.
00:35
So subbing this into the expression for the lorentz factor, we find that the lorentz factor is equal to 2 .03.
00:43
So now what we need to do is substitute these values into this expression here.
00:48
So we can say that momentum is equal to the lorentz factor, so 2 .03, multiplied by the mass, which is 12 .6 kilograms, multiplied by its velocity, which is 0 .87 times 3 times 10 to the 8, because it's multiplied by the speed of light.
01:17
And this gives us a momentum equal to 66 .7586 times 10 to the 8 kilogram metres per second...