Respuesta :
Answer:
i. a = -6 ii. b = 12 iii. 100 iv. 26.6°
Step-by-step explanation:
Since the weight of the object is 20 N and directed downwards, its vector is -20j. Now, since the particle is in suspension, AP + BP = -20j
So, since AP = ai + 8j and BP = 6i + bj,
AP + BP = -20j
ai + 8j + 6i + bj = -20j
ai + 6i + 8j + bj = -20j
(a + 6)i + (8 + b)j = -20j
(a + 6)i + (8 + b)j = 0i - 20j
equating the components on both sids,
a + 6 = 0 and 8 + b = 20
a = -6 and b = 20 - 8 = 12
i. The value of a is -6
ii. The value of b is 12
iii. The magnitude of the tension in string AP is?
since AP = ai + 8j = -6i + 8j
magnitude of AP = √[-6² + 8²] = √[36 + 64] = √100 = 10
iv. The angle that string BP makes with the vertical is?
Since BP = 6i + bj = 6i + 12j, the angle it makes with the horizontal is Ф = tan⁻¹(12/6) = tan⁻¹(2) = 63.44°.
Thus, the angle it makes with the vertical is thus 90° - 63.44° = 26.56° (complementary angles) ≅ 26.6° to 3 s.f
1) The values of a and b of the given vectors are respectively; -6 and 12
2) The magnitude of the tension in string AP is; 10
3) The angle that string BP makes with the vertical is; 26.6°
What is the magnitude of the tension?
We are told that the weight of the particle P is 20 N. Since the particle is suspended by two strings, then its' direction is downwards and as such its vector is -20j.
By equilibrium;
AP + BP = -20j
1) We are given the tension vectors;
AP = ai + 8j and BP = 6i + bj,
Thus;
ai + 8j + 6i + bj = -20j
(ai + 6i) + (8j + bj) = -20j
(a + 6)i + (8 + b)j = -20j
(a + 6)i + (8 + b)j = 0i - 20j
Equating the components of both sides gives;
a + 6 = 0 and 8 + b = 20
Solving gives;
a = -6 and b = 20 - 8 = 12
Thus, the values of a and b are -6 and 12
2) The magnitude of the tension in string AP is gotten from resolution of the tension vector AP;
AP = ai + 8j = -6i + 8j
Thus, magnitude of AP = √(-6² + 8²) = √(36 + 64) = √100 = 10
3) The angle that string BP makes with the vertical is gotten from;
BP = 6i + bj = 6i + 12j
Thus, the angle it makes with the horizontal;
θ = tan⁻¹(12/6) = tan⁻¹(2) = 63.44°.
Angle it makes with the vertical = 90° - 63.44° = 26.56° ≈ 26.6°
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