Question

Resultant of P vector and Q vector inclined at an angle theta is R vector
find theta if magnitude of R vector=mag of P vector=mag of Q vector

Answer 1

Answer:

R vector = (p^2+q^2+2pq*cos theta) whole root

as p=q=r write all p and q as r

therefore, r = (r^2+r^2+ 2r^2* cos theta ) whole root

taking square both side as in rhs their is square root

-r^2/2r^2 = cos theta

-1/2 = cos theta

therefore theta = 120 degree

Explanation:

Answer 2

Explanation:

When the angle is θ, the magnitude of resultant is

2P= ✓P ²+Q ²+2PQcosθ

When the angle is 180−θ, the magnitude of resultant is

P=✓ P ² +Q ²+2PQcos(180−θ)

Squaring and adding the two equations, we get

2P ²+2Q ² =5P²

2Q² =3P²

p/q = ✓2/3