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Grade 11Mechanics

Determine the horizontal force required to displace a mass of 0.03 KG suspended by a string until the string makes an angle 30 degree with the vertical. Please solve it by method of resolution of vectors.

Question image for Determine the horizontal force required to displa

Akshita

7 Years agoGrade 11

2 Answers

sree lakshmi

7 Years ago

Given that mass =0.03kg

Length of string =l

Using the law of conservation of mechanical energy

Work done by the horizontal force= gain in PE

ie

F×l sin30 =mgl(1-cos30)

F=mg(1-cos30)/sin30

F=0.03×10×(1-√3/2)÷1/2

=0.3×(2-√3)

=0.0804 N

Khimraj

7 Years ago

Given,
m = 0.03 kg
Using the law of conservation of mechanical energy,
Work done by the horizontal force = Gain in P. E. of mass m
or, F × 1 sin 30° = mg × ( 1 - 1 cos 30°)
or, F = mg × (1 -1 cos 30°)/1 sin 30°
= 0.03 g × (1 - √3/2)/(1/2)
= 0.03 g × (2 - √3/2)/(1/2)
= 0.03 g × (2 - √3)
= 0.03 g × 9.8 × (2 - √3)
= 0.079 N Answer

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