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Concepts Of Physics MCQ Edition [Volume 1]

Exam: Concepts Of Physics MCQ Edition [Volume 1]
Subject: Physics
Chapter: Newton's Laws of Motion

Concepts Of Physics MCQ Edition [Volume 1] · Physics · Newton's Laws of Motion

A pendulum bob of mass 50 g hangs from the ceiling of an elevator....

A pendulum bob of mass

50 \text{ g}

hangs from the ceiling of an elevator. Determine the tension in the string given that the elevator is travelling downward with an acceleration of

1.2 \text{ m/s}^2

.

Options

A $0.49 \text{ N}$
B $0.43 \text{ N}$
C $0.55 \text{ N}$
D $0.44 \text{ N}$

Correct answer

B. $0.43 \text{ N}$

Step-by-step solution

Given mass of the bob,

m = 50 \text{ g} = 0.05 \text{ kg}

Acceleration of the elevator,

a = 1.2 \text{ m/s}^2

downward

Acceleration due to gravity,

g = 9.8 \text{ m/s}^2

When the elevator accelerates downward, the equation of motion for the bob is:

mg - T = ma

T = m(g - a)

Substituting the given values:

T = 0.05(9.8 - 1.2)

T = 0.05 \times 8.6 = 0.43 \text{ N}

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