Question

Two forces 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. $0^\circ$
• B. $60^\circ$
• C. $90^\circ$
• D. $45^\circ$

Answer 1

Answer: (A)

$0^\circ$

Answer 2

3F = F + 2F
$R^2 = P^2 + Q^2 + 2PQ cos?$
$9F^2 = F^2 + 4F^2 + 4F^2 cos?$
$cos? = 1$
$? = 0^\circ$