00:06Question is, consider two vectors F1 is equal to 2i plus 5k and F2 is equal to 3j plus 4k.
00:20Okay, the magnitude of the scalar product of these vectors is a20, b23, c5 under root 33, d26.
00:34As we have to find the magnitude of the scalar product means dot product of two forces.
00:41So, F1 dot F2 is equal to the value of F1 is 2i plus 5k dot the value of F2
01:04is 3j plus
01:104k.
01:13So, F1 dot F2 is equal to, first we will take 2i.
01:25So, 2i dot 3j plus 4k and then we will multiply plus 5k.
01:36So, plus 5k dot 3j plus 4k.
01:45So, F1 dot F2 will be equal to 2, 3, d6 i dot j plus 2, 4, d8 i dot
02:04k plus 5, 3, d15 k dot j.
02:20So, F1 dot F2 is equal to, is, i dot j, i dot k is equal to, k dot j
02:39is equal to 0.
02:41Means, they all will become 0.
02:45So, 6 into 0 plus 6 into 0 plus 8 into 0 plus 15 into 0 plus 20 is, i
03:01dot i is equal to 1, j dot j is equal to 1 and k dot k is also equal
03:10to 1.
03:12So, k dot k will be equal to 1, so into 1.
03:18So, F1 dot F2 will be equal to 0 plus 0 plus 0 plus 20 into 1, it will be
03:3020.
03:30So, F1 dot F2 will be equal to 20.
03:38So, the correct option will be a 20.
03:45So, F1 dot f2 will be equal to 0 plus 0 plus 0 plus 0 which will be equal to
03:461 asbasi.
03:46You
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