QJEEM19Ph50b3: JEE Main 2019 Physics - Class 11 JEEM19Ph50b3 Solution: Two forces P and Q, of magnitude 2F and 3F, respectively, are…

Question

Verified Solution • 2025–26 Session moderate

Two forces P and Q, of magnitude 2F and 3F, respectively, are at an angle

θ

with each other. If the force Q is doubled, then their resultant also gets doubled. Then, the angle

θ

is -

Accepted Answer

4F² + 9F² + 12F² cos

θ

= R²

4F² + 36F² + 24F² cos

θ

= 4R²

4F² + 36F² + 24F² cos

θ

= 4(13F² + 12F²cos

θ

) = 52F² + 48F²cos

θ

cos

θ

=

-

\frac{12 F^{2}}{24 F^{2}}

=

-

\frac{1}{2}

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