Question

Two force in the ratio $1:2$ act simultaneously on a particle. The resultant of these forces is three times the first force. The angle between them is:

• A. $0^o$
• B. ${60}^o$
• C. ${90}^o$
• D. ${45}^o$
• E. ${30}^o$

Answer 1

The correct option is A $0^o$

Resultant force magnitude=$\sqrt{F_1^2+F_2^2+2F_1{F}_{2}cos\theta }$

3=$\sqrt{1^2+2^2+2\times 1\times 2cos\theta }$

On solving $\theta =0°$