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Particles 1 and 2 each mass m fixed to the ends of a rigid massless rod of length L1 + l2 with L1 = 20cm and l2 = 80 cm. The rod is held horizontally on the fulcrum and then released. What are the magnitudes of the initial accelerations of particles 1 and 2.

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Final answer:

To calculate the magnitudes of the initial accelerations of particles 1 and 2, we can use the equation for rotational motion and the concept of moment of inertia.

Step-by-step explanation:

When the rod is released, it will rotate about the fulcrum due to the difference in distances of the masses from the fulcrum. The initial accelerations of particles 1 and 2 can be calculated using the equation for rotational motion:

α = (mass of particle × distance from fulcrum) / (moment of inertia)

Since the rod is rigid and massless, the moment of inertia can be calculated as:

Moment of inertia = (m₁ × L₁² + m₂ × L₂²)

Substituting the expressions for torque and moment of inertia into the torque equation:

m × g × L₁ + m × g × L2 = (m × L₁ ² + m × L₂²) × α

Solving for α:

α = g × (L₁ + L₂) / (L₁² + L₂²)

Calculate the initial accelerations:

The initial accelerations of the particles are related to the angular acceleration by:

a₁ = α × L₁

a₂ = α × L₂

7. Plug in the values and calculate the initial accelerations:

α = (9.81 m/s²) × (0.2 m + 0.8 m) / (0.2² m² + 0.8² m²) ≈ 4.76 rad/s²

a₁ = 4.76 rad/s² × 0.2 m ≈ 0.95 m/s²

a₂ = 4.76 rad/s² × 0.8 m ≈ 3.81 m/s²

Therefore, the initial accelerations of particles 1 and 2 are approximately 0.95 m/s² and 3.81 m/s², respectively.

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