Question

1) Dois vetores, de módulos iguais a 4 e 1, formam entre si um ângulo de 600. Determine o módulo da resultante desses vetores. * O a) 13 O b) vo O c) v21 O d) 19 O e) 5​

Answer 1

Pela regra do paralelogramo

v_{r}^{2}=v_{1}^{2}+v_{2}^{2}-2.v_{1}.v_{2}. \cos{\theta}v

r

2

=v

1

2

+v

2

2

−2.v

1

.v

2

.cosθ

\begin{gathered}v_{r}^{2}=v_{1}^{2}+v_{2}^{2}-2.v_{1}.v_{2}. \cos{\theta} \\ v_{r}^{2}={3}^{2}+{2}^{2}-2.3.2.\cos{120\degree}\end{gathered}

v

r

2

=v

1

2

+v

2

2

−2.v

1

.v

2

.cosθ

v

r

2

=3

2

+2

2

−2.3.2.cos120°

\begin{gathered}v_{r}^{2}=9+4-2.3.\cancel2.(-\frac{1}{\cancel2}) \\ v_ {r}^{2} = 13 + 6 \\ v_{r} = \sqrt{19} \end{gathered}

v

r

2

=9+4−2.3.

2

.(−

2

1

)

v

r

2

=13+6

v

r

=

19

R: 19O