00:01
So in this question we're told that we have two forces on a box.
00:04
So the box has a mass of 1 .87 kilograms.
00:08
There's a force f1, and f1 is 13 .8 newtons along the x axis.
00:18
There's an acceleration, a, which forms an angle theta equals 21 .5 degrees with the negative y axis.
00:30
And it has magnitude of 10 .8 meters per second squared.
00:38
And there's another force that, and we don't know what it is.
00:41
So we're going to call that other force f2, and we know that f1 plus f2 is going to be ma.
00:50
So f2 is going to be ma minus f1.
00:59
Now a is going to be, so 10.
01:09
And in the x direction it's going to be minus sine theta and in the y direction it's going to be minus 10 .8 m cos theta but then in the i direction we also have minus f1 which is minus 13 .8 newtons in the i direction so let's work this out so in the i direction we have a 10.
01:49
1 .8 times m which is 1 .87 times minus sign theta so minus sign of 21 .5 degrees and this gives us minus 7 .40 and then we also have minus 13 .8 and in the j direction we have minus 10m cos theta which is minus 18 .79 so this gives us 7 .4 plus 13 .8, which is minus 21 .2 in the i direction, minus 18 .79.
02:44
Let's round it to one decimal place.
02:48
18 .8...