Two forces P and Q of magnitude 2F and 3F, respectively, are at an angle with each other. If the force Q is doubled, then their resultant also gets doubled. Then, the angle is: |
|||

(a) |
30 |
(b) |
60 |

(c) |
90 |
(d) |
120 |

Two forces P and Q of magnitude 2F and 3F, respectively, are at an angle with each other. If the force Q is doubled, then their resultant also gets doubled. Then, the angle is: |
|||

(a) |
30 |
(b) |
60 |

(c) |
90 |
(d) |
120 |

1 Answer - 5876 Votes

3537

4F^{2}+9F^{2}+12F^{2}cos=R^{2}

4F^{2}+36 F^{2}+24 F^{2 }cos=4R^{2}

4F^{2}+36 F^{2}+24 F^{2}cos

=4(13F^{2}+12F^{2}cos)= 52 F^{2} +48F^{2}cos

cos ==