Question

Physics
The resultant of two forces, one double the other in
magnitude is perpendicular to the smaller of the two
forces. The angle between the two forces is
A
150°
B 90°
C 60°
D 120°

Answer 1

Let the two forces be F1 and F2 are given according to question ∣F1∣=2∣F2∣

Resultant of two forces F1 and F2 are given by

R=F1+F2

R is perpendicular upon smaller force

Here smaller forces F2

So R.F2=0

⇒(F1+F2).F2=0⇒F1.F2+F22=0⇒∣F1∣∣F2∣cosϕ+∣F2∣2=0

Putting ∣F1∣=2∣F2∣

⇒2∣F2∣∣F2∣cosϕ+∣F2∣2=0⇒2cosϕ+1=0⇒cosϕ=−21=

HOPE IT HELPS :)

Answer 2

Answer:

ANSWER

C

=

A

+

B

∠

A

B

=θ

C

⊥

B

A=2B

C

⋅

B

=0

⇒(

A

+

B

)⋅

B

=0

⇒

A

⋅

B

+B

2

=0

⇒2B

2

cosθ+B

2

=0

⇒cosθ=−

2

1

⇒θ=

3

2π

Explanation:

I hope it helps you