How do you derive an expression for the net torque …

Physics Questions

How do you derive an expression for the net torque exerted on a two-student-board system about its support, given that one student has mass M0 and the other has mass 2.5 * M0? Which student should move closer to the support in order to balance the board horizontally without touching the ground, and what is the reasoning behind your choice? Additionally, how can you derive the distance the chosen student should move, and determine the magnitude of the force exerted on the board once it is balanced? Please express all answers in terms of M0, Lb, and relevant physical constants.

Short Answer

The concept of torque involves calculating the product of force and distance from a pivot point to ensure balance. To achieve equilibrium, the sum of torques from both students reveals that the heavier student must move 0.2 L closer to the center, balancing the system effectively.

Step-by-Step Solution

Step 1: Understand the Concept of Torque

Torque is defined as the product of force and distance from the pivot point. To keep an object balanced, we need to evaluate the sum of torques acting around a certain point, usually the center. The formula for calculating torque is:

  • Torque (œN) = Force (F) x Distance (d)

Step 2: Calculate the Net Torque

To determine if a system is in equilibrium, we need to find the sum of torques acting on the system. Here, we compute the torques for both students, which gives us:

  • Torque of heavier student: (2.5 M‚ÄöCA g)(L/2)
  • Torque of lighter student: (M‚ÄöCC g)(L/2)

The sum of these torques results in 0.75 M‚ÄöCA g L, indicating the need for adjustments to achieve balance.

Step 3: Adjust Student Positions for Balance

To achieve a state of balance where the net torque equals zero, the heavier student must move closer to the center. By setting up the equation for torque balance:

  • 0 = (2.5 M‚ÄöCA g)(x) – (M‚ÄöCC g)(L/2)

Solving for the distance (x) reveals that the heavier student should move 0.2 L towards the center to maintain balance. This ensures that the board remains stable and does not accelerate.

Related Concepts

Torque

The product of force and distance from the pivot point, which determines the rotational force acting on an object.

Net Torque

The sum of all torques acting on a system, used to assess whether the system is in equilibrium.

Equilibrium

A state where the net force and net torque acting on an object are both zero, resulting in no acceleration or movement.

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