Mechanical Engineering - Engineering Mechanics - Discussion

Discussion Forum : Engineering Mechanics - Section 1 (Q.No. 10)
10.
If the resultant of two equal forces has the same magnitude as either of the forces, then the angle between the two forces is
30°
60°
90°
120°
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
35 comments Page 2 of 4.

ABE said:   8 years ago
R= √(A^2+B^2+2ABcosθ).
Here A=F,B=F ;We need R=F
squaring on bhs.

F^2 =2F^2+2F^2cosα
on solving,
-F^2=2F^2cosα.
cosα=-0.5.
α=120 DEGREE.

Shams said:   10 years ago
The angle is 60 and not 120. It can be clearly understood from equilateral triangle and total angle in a triangle. And also from the cosine rule: A^2 = B^2+C^2-2BC cosA.

Kesav said:   4 years ago
According to Lamis theorem, sine α = sine β = sine γ.

i.e. α + β + γ =360 so 360 /3 =120 =α = β= γ.
(29)

Murali Raj K said:   10 years ago
Both the forces are equal thus the resultant is also equal.

Total angle is 360.

Three forces are acting equally thus 360/3=120.

P.Chilambarasan said:   9 years ago
R^2 = P^2 + q^2 + 2pq Cosθ.
R = P = Q = F.

Substitute F in the equation, you get Cosθ = -1.
So, θ = 180°.

Dhanendra said:   9 years ago
Correct answer will be 60θ as in fcosθ plus fcosθ equal to f which gives θ equal to 60θ.

Krushna said:   1 decade ago
Total space angle is 360.
To forces having same magnitude.

And resultant also having same of both.
So 360/3 = 120.

Ankit ughade said:   9 years ago
For getting the equilibrium condition all these forces must have the same angle to each other.

Hence 360/3 = 120.

Abdul Khaleque said:   10 years ago
p2 = p2+p2+2p.pcosθ.
p2 = 2p2+2p2cosθ.

-p2 = 2p2cosθ.
cosθ = -1/2.
θ = 120.

Mohan said:   8 years ago
Resultant force is equal to either of two forces. Not that all forces have a same magnitude.


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