Question

Solve questions no 4 and 5 please

Answer 1

Explanation:

Q.4

Let R be the resultant of the two equal Forces F1 and F2.

By the given conditions

R = F = F

$r = \sqrt{ {r}^{2} + {r}^{2} + 2 {r}^{2} \cos( \alpha ) } \\ \\ \\ squaring \: on \: both \: sides \: \\ \\ \\ {r}^{2} = 2 {r}^{2} +2 {r}^{2} \cos( \alpha ) \\ \\ \\ {r}^{2} = 2 {r}^{2} (1 + \cos( \alpha ) ) \\ \\ \\ \frac{1}{2} = 1 + \cos( \alpha ) \\ \\ \\ \cos( \alpha ) = - \frac{1}{2} \\ \\ \\ \alpha = 120$

Q.5

V1 = 2i + 3j + 4k

V2 = 3i + 2j - 4k

$v1 = \sqrt{ {2}^{2} + {3}^{2} + {4}^{2} } \\ \\ \\ = \sqrt{4 + 9 + 16} \\ \\ \\ = \sqrt{29} \\ \\ \\ v2 = \sqrt{ {3}^{2} + {2}^{2} + { - 4}^{2} } \\ \\ \\ = \sqrt{9 + 16 + 4} \\ \\ \\ = \sqrt{29}$

[ NOTE : bold letters represent the vector and normal letter shows magnitude of the vector ]

THANKS