Connected Bodies & Pulleys — MH-CET Physics MCQs with Solutions
Free MH-CET Physics Connected Bodies & Pulleys MCQs with step-by-step solutions (21 questions). Part of Laws of Motion (Std 11). Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Connected Bodies & Pulleys · easy · theory
The tension throughout a light inextensible string passing over a smooth pulley is:
A. Greater near the heavier mass
B. Zero
C. Greater near the lighter mass
D. The same everywhere ✓ Correct
Solution: A massless string and frictionless pulley cannot support any difference in tension.
Q2 — Connected Bodies & Pulleys · medium · theory
Two bodies connected by an inextensible string have:
A. Equal velocities at all times regardless of direction
B. Accelerations in the ratio of their masses
C. Independent accelerations
D. Accelerations of equal magnitude ✓ Correct
Solution: The inextensibility of the string is the constraint that links their motions.
Q3 — Connected Bodies & Pulleys · easy · theory
A free body diagram is used to:
A. Show all the forces acting on a single chosen body ✓ Correct
B. Show the forces acting on the whole system at once
C. Show the velocities of the bodies
D. Show only the applied forces
Solution: Isolating one body at a time makes the equations of motion straightforward.
Q4 — Connected Bodies & Pulleys · medium · theory
In an Atwood machine, the acceleration of the system depends on:
A. The difference and sum of the two masses ✓ Correct
B. The radius of the pulley only
C. The length of the string
D. The product of the two masses only
Solution: $a = \dfrac{(m_2 - m_1)g}{m_1 + m_2}$.
Q5 — Connected Bodies & Pulleys · hard · theory
The tension in the string of an Atwood machine with unequal masses is:
A. Less than both weights
B. Less than the weight of the heavier mass and more than that of the lighter ✓ Correct
C. Greater than both weights
D. Equal to the sum of the weights
Solution: The heavier mass accelerates downward, so the tension cannot fully support it.
Q6 — Connected Bodies & Pulleys · medium · theory
When two blocks in contact are pushed by a force, the contact force between them:
A. Is an action-reaction pair acting on the two blocks ✓ Correct
B. Equals the applied force
C. Is zero if the surface is smooth
D. Acts only on the front block
Solution: By Newton's third law each block pushes the other equally and oppositely.
Q7 — Connected Bodies & Pulleys · medium · theory
For a body hanging in a lift accelerating upward, the tension in the supporting string is:
A. Zero
B. Greater than the weight of the body ✓ Correct
C. Less than the weight of the body
D. Equal to the weight of the body
Solution: $T = m(g + a)$, since the string must both support and accelerate the body.
Q8 — Connected Bodies & Pulleys · hard · theory
In analysing a system of connected bodies, the system approach is useful because:
A. Internal forces cancel, leaving only external forces to consider ✓ Correct
B. It avoids the need for any equations
C. It applies only to smooth surfaces
D. It gives the tension directly
Solution: To find internal tensions one must still isolate individual bodies.
Q9 — Connected Bodies & Pulleys · medium · theory
A smooth pulley in an ideal system serves to:
A. Change the direction of the tension without changing its magnitude ✓ Correct
B. Increase the tension in the string
C. Provide the accelerating force
D. Reduce the tension in the string
Solution: An ideal pulley is massless and frictionless.
Q10 — Connected Bodies & Pulleys · hard · numerical
Masses of $2\text{ kg}$ and $3\text{ kg}$ hang from the ends of a string over a smooth pulley. The acceleration of the system is ($g = 10\text{ m/s}^2$):
A. $2\text{ m/s}^2$ ✓ Correct
B. $10\text{ m/s}^2$
C. $1\text{ m/s}^2$
D. $5\text{ m/s}^2$
Solution: $a = \dfrac{(3 - 2) \times 10}{2 + 3} = \dfrac{10}{5} = 2\text{ m/s}^2$.
Q11 — Connected Bodies & Pulleys · hard · numerical
For the same Atwood machine ($2\text{ kg}$ and $3\text{ kg}$), the tension in the string is:
A. $20\text{ N}$
B. $50\text{ N}$
C. $24\text{ N}$ ✓ Correct
D. $30\text{ N}$
Solution: $T = \dfrac{2m_1m_2g}{m_1 + m_2} = \dfrac{2 \times 2 \times 3 \times 10}{5} = 24\text{ N}$.
Q12 — Connected Bodies & Pulleys · medium · numerical
Masses of $4\text{ kg}$ and $6\text{ kg}$ hang over a smooth pulley. The acceleration of the system is ($g = 10\text{ m/s}^2$):
A. $2\text{ m/s}^2$ ✓ Correct
B. $4\text{ m/s}^2$
C. $5\text{ m/s}^2$
D. $1\text{ m/s}^2$
Solution: $a = \dfrac{(6 - 4) \times 10}{10} = 2\text{ m/s}^2$.
Q13 — Connected Bodies & Pulleys · hard · numerical
For the Atwood machine with $4\text{ kg}$ and $6\text{ kg}$, the tension is:
A. $40\text{ N}$
B. $100\text{ N}$
C. $60\text{ N}$
D. $48\text{ N}$ ✓ Correct
Solution: $T = \dfrac{2 \times 4 \times 6 \times 10}{10} = 48\text{ N}$.
Q14 — Connected Bodies & Pulleys · medium · numerical
Blocks of $2\text{ kg}$ and $3\text{ kg}$ in contact on a smooth table are pushed by a force of $10\text{ N}$. The acceleration is:
A. $2\text{ m/s}^2$ ✓ Correct
B. $1\text{ m/s}^2$
C. $5\text{ m/s}^2$
D. $3.3\text{ m/s}^2$
Solution: $a = \dfrac{F}{m_1 + m_2} = \dfrac{10}{5} = 2\text{ m/s}^2$.
Q15 — Connected Bodies & Pulleys · hard · numerical
For the same two blocks ($2\text{ kg}$ pushed against $3\text{ kg}$, $a = 2\text{ m/s}^2$), the contact force between them is:
A. $5\text{ N}$
B. $6\text{ N}$ ✓ Correct
C. $10\text{ N}$
D. $4\text{ N}$
Solution: The contact force accelerates the $3\text{ kg}$ block alone: $F = 3 \times 2 = 6\text{ N}$.
Q16 — Connected Bodies & Pulleys · easy · numerical
Two equal masses hang from the ends of a string over a smooth pulley. The acceleration of the system is:
A. $g$
B. $2g$
C. $\dfrac{g}{2}$
D. Zero ✓ Correct
Solution: With no net driving force the system stays in equilibrium.
Q17 — Connected Bodies & Pulleys · easy · numerical
A block of mass $5\text{ kg}$ on a smooth surface is pulled by a string with a force of $20\text{ N}$. Its acceleration is:
A. $0.25\text{ m/s}^2$
B. $25\text{ m/s}^2$
C. $4\text{ m/s}^2$ ✓ Correct
D. $100\text{ m/s}^2$
Solution: $a = \dfrac{20}{5} = 4\text{ m/s}^2$.
Q18 — Connected Bodies & Pulleys · medium · numerical
Three blocks of $1\text{ kg}$, $2\text{ kg}$ and $3\text{ kg}$ connected in a line on a smooth surface are pulled by a force of $12\text{ N}$. The acceleration is:
A. $6\text{ m/s}^2$
B. $12\text{ m/s}^2$
C. $4\text{ m/s}^2$
D. $2\text{ m/s}^2$ ✓ Correct
Solution: $a = \dfrac{12}{1 + 2 + 3} = 2\text{ m/s}^2$.
Q19 — Connected Bodies & Pulleys · hard · numerical
For the three blocks of the previous type (pulled from the $1\text{ kg}$ end, $a = 2\text{ m/s}^2$), the tension between the $1\text{ kg}$ and $2\text{ kg}$ blocks is:
A. $10\text{ N}$ ✓ Correct
B. $12\text{ N}$
C. $2\text{ N}$
D. $6\text{ N}$
Solution: That tension accelerates the $2\text{ kg}$ and $3\text{ kg}$ blocks: $T = 5 \times 2 = 10\text{ N}$.
Q20 — Connected Bodies & Pulleys · hard · numerical
A mass of $2\text{ kg}$ hangs from the ceiling of a lift accelerating upward at $2\text{ m/s}^2$. The tension in the string is ($g = 10\text{ m/s}^2$):
A. $24\text{ N}$ ✓ Correct
B. $4\text{ N}$
C. $16\text{ N}$
D. $20\text{ N}$
Solution: $T = m(g + a) = 2 \times 12 = 24\text{ N}$.
Q21 — Connected Bodies & Pulleys · medium · numerical
A body hangs from a spring balance in a lift moving upward with constant velocity. The reading of the balance is:
A. Greater than the true weight
B. Zero
C. Less than the true weight
D. Equal to the true weight of the body ✓ Correct
Solution: Constant velocity means zero acceleration, so the tension equals $mg$.