Concepts Of Physics MCQ Edition [Volume 1]PhysicsRotational Mechanics
As depicted in the figure, two blocks of masses m and M are linked by a string that passes over a pulley. The horizontal table on which the mass m slides is smooth. The pulley, which can freely rotate about its axis, has a radius r and a moment of inertia I about this axis. Determine the acceleration of the mass M , assuming the string does not slip on the pulley.
Options
- AMg M - m + I/r^2
- BMg M + m + I r^2
- Cmg M + m + I/r^2
- DMg M + m + I/r^2
Correct answer
D. Mg M + m + I/r^2
Step-by-step solution
Let a be the acceleration of the blocks and be the angular acceleration of the pulley. Since the string does not slip on the pulley, the relation between linear and angular acceleration is a = r . Let T₁ be the tension in the horizontal segment of the string attached to mass m , and T₂ be the tension in the vertical segment attached to mass M . Writing the equations of motion for each component: For mass M (moving downwards): Mg - T₂ = Ma For mass m (moving horizontally on a smooth table): T₁ = ma For the pulley (r