Find that greek thing..

JEE Advanced 2015 Sample Questions › Mechanics questions › Find that greek thing..

A simple pendulum consists of a bob of mass 'm' attached to a string of breaking strength double the weight of the bob. The bob is released from rest vertically when the string is horizontal. The string breaks when it makes an angle Î¸ with the vertical. Find Î¸.

a) cos^-1 1/3
b) cos^-1 2/3
c)60Â°
d)0Â°

#Physics #Mechanics

UP 0 DOWN 0 0 4
Post on FacebookPost anonymously?

4 Answers

1

ANKIT MAHATO ·2009-07-01 00:54:22

b) cos-1 2/3

UP 0 DOWN 0
Post on FacebookPost anonymously?

1

ANKIT MAHATO ·2009-07-01 00:57:59

energy conservation :

mgl = mgl(1 - cosÎ¸) + 1/2 m v²
m v² = 2mglcosÎ¸

force eq the string will break if the frce is 2mg

mgcosÎ¸ + m v²/l = 2mg
3mgcosÎ¸ = 2mg

cos Î¸ = 2/3

UP 0 DOWN 0
Post on FacebookPost anonymously?

1

Ritika ·2009-07-01 07:18:11

thx a lot.

UP 0 DOWN 0
Post on FacebookPost anonymously?

1

ANKIT MAHATO ·2009-07-02 22:14:56

welcome :)

UP 0 DOWN 0
Post on FacebookPost anonymously?

Your Answer

Basic Integral Calculus Operators Symbols Matrix Cases

√ √ || {} [] () → ~ ^ x x x → → ln log lg lim lim cos sin tan cot arcsin arccos arctan

∫ ∫ ∫ ∫ ∫ ∬ ∬ ∬ ∬ ∬ ∭ ∭ ∭ ∭ ∭ ⨌ ⨌ ⨌ ⨌ ⨌

∑ ∑ ∑ ∑ ∑ ∮ ∮ ∮ ∮ ∮ ∏ ∏ ∏ ∏ ∏ ∐ ∐ ∐ ∐ ∐

+ - × ÷ ± ∓ = ∪ ∩ ≠ ∼ ≈ ∅ ∀ ∃ ∈ ∋ ∝ ≤ ≥ ≃ ≅ ≡ < > ≪ ≫ ⊂ ∉ ⊃ ⊆ ⊇ ⇒ ⇐ ⇔ ⇒ ⇐ ⇔ ⇑ ⇓ ⇕ → ← ↔ → ← ↔ ↑ ↓ ↕ ↖ ↗ ↘ ↙ ↪ ↩ ⇀ ↼ ⇁ ↽

° ∂ ∞ α β γ δ θ λ μ ν ξ π ρ σ φ ω ε ƒ κ τ υ Γ Δ Λ Σ Π Ω