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# Part (a) – To determine the acceleration of the system
| Step | Derivation/Formula | Reasoning |
|---|---|---|
| 1 | [katex]T_1 – T_2 = I \alpha [/katex] | This equation represents the relationship between the tensions on either side of the pulley ([katex]T_1[/katex] and [katex]T_2[/katex]), the moment of inertia of the pulley ([katex]I[/katex]), and the angular acceleration ([katex]\alpha[/katex]). |
| 2 | [katex]I = \frac{1}{2} m_p r^2[/katex] | The moment of inertia ([katex]I[/katex]) of a disk-shaped pulley, where [katex]m_p[/katex] is the mass of the pulley and [katex]r[/katex] is its radius. |
| 3 | [katex]\alpha = a/r[/katex] | The angular acceleration ([katex]\alpha[/katex]) is related to the linear acceleration ([katex]a[/katex]) of the falling mass by the radius of the pulley ([katex]r[/katex]). |
| 4 | [katex]f_k = \mu_k T_s[/katex] | The frictional force [katex]f_k[/katex] is calculated using the coefficient of kinetic friction ([katex]\mu_k[/katex]) and the tangential component of the tension [katex]T_s[/katex], which can be approximated as [katex]T_s = (T_1 + T_2)/2[/katex]. |
| 5 | [katex]T_1 – T_2 – f_k r = I \alpha[/katex] | Combine the effects of tension and frictional force (considering the friction opposes the motion thus negative), and include the effect of the pulley’s inertia. |
| 6 | [katex](m_2 g – T_2) – (T_1 – m_1 g) = (m_1 + m_2) a[/katex] | The forces acting on the blocks ([katex]m_1 g – T_1[/katex] downwards on [katex]m_1[/katex] and [katex]m_2 g – T_2[/katex] downwards on [katex]m_2[/katex], assuming [katex]m_1[/katex] < [katex]m_2[/katex] so [katex]m_2[/katex] descends) produces the net force, which equals the total system mass times the system’s acceleration. |
| 7 | Solve for [katex]a[/katex] using the equations | Combine all equations replacing [katex]\alpha[/katex] with [katex]a/r[/katex] and solve for [katex]a[/katex] to get the system’s acceleration, involving simplifications and algebraic manipulation. |
# Part (b) – To determine the tension in the rope
| Step | Derivation/Formula | Reasoning |
|---|---|---|
| 1 | [katex]m_1 g – T_1 = m_1 a[/katex] | For mass [katex]m_1[/katex], the net force is the difference between the weight and the tension, which equals its mass times acceleration. |
| 2 | [katex]T_1 = m_1 g – m_1 a[/katex] | Solving the above equation for [katex]T_1[/katex] gives the tension in the rope on the side of mass [katex]m_1[/katex]. |
| 3 | [katex]T_1[/katex] calculation | Plug the values of [katex]g[/katex], [katex]m_1[/katex], and [katex]a[/katex] obtained from part (a) to find [katex]T_1[/katex]. |
# Part (c) – To determine the magnitude and direction of the frictional force exerted on the pulley
| Step | Derivation/Formula | Reasoning |
|---|---|---|
| 1 | [katex]f_k = \mu_k \frac{T_1 + T_2}{2}[/katex] | Using the approximation that the mean tension provides the force of friction calculation against the direction of motion. |
| 2 | [katex]f_k[/katex] calculation | Calculate the value by substituting [katex]\mu_k[/katex], [katex]T_1[/katex], and [katex]T_2[/katex] values (where [katex]T_2[/katex] can be similarly calculated like [katex]T_1[/katex]). |
| 3 | [katex]f_k[/katex] direction determination | The frictional force opposes the direction of relative motion between the rope and the pulley, which will be clockwise due to the motion of [katex]m_2[/katex] falling downward. |
This sequence of tables will help in understanding the steps involved thoroughly to solve the given problem numerically. Please note the precise solutions would require the use of actual numerical values derived or given directly in the problem (e.g., gravitational acceleration [katex] g = 9.8 \, \text{m/s}^2 [/katex]).
Just ask: "Help me solve this problem."
A seesaw is balanced on a fulcrum, with a boy of mass [katex] M_1 [/katex] sitting on one end and a girl of mass [katex] M_2 [/katex] sitting on the other end. The seesaw is a uniform plank of length [katex]L[/katex] and mass [katex] M[/katex]. The fulcrum is located at the midpoint of the plank. Does [katex] M_1 = M_2 [/katex]. Justify your working.
An object moves at a constant speed of [katex] 9.0 \frac{m}{s} [/katex] in a circular path of radius of 1.5 m. What is the angular acceleration of the object?
Five forces act on a rod that is free to pivot at point P, as shown in the figure. Which of these forces is producing a counter-clockwise torque about point P?
A merry-go-round spins freely when Diego moves quickly to the center along a radius of the merry-go-round. As he does this, it is true to say that
Consider a uniform hoop of radius R and mass M rolling without slipping. Which is larger, its translational kinetic energy or its rotational kinetic energy?
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| Kinematics | Forces |
|---|---|
| \(\Delta x = v_i t + \frac{1}{2} at^2\) | \(F = ma\) |
| \(v = v_i + at\) | \(F_g = \frac{G m_1 m_2}{r^2}\) |
| \(v^2 = v_i^2 + 2a \Delta x\) | \(f = \mu N\) |
| \(\Delta x = \frac{v_i + v}{2} t\) | \(F_s =-kx\) |
| \(v^2 = v_f^2 \,-\, 2a \Delta x\) |
| Circular Motion | Energy |
|---|---|
| \(F_c = \frac{mv^2}{r}\) | \(KE = \frac{1}{2} mv^2\) |
| \(a_c = \frac{v^2}{r}\) | \(PE = mgh\) |
| \(T = 2\pi \sqrt{\frac{r}{g}}\) | \(KE_i + PE_i = KE_f + PE_f\) |
| \(W = Fd \cos\theta\) |
| Momentum | Torque and Rotations |
|---|---|
| \(p = mv\) | \(\tau = r \cdot F \cdot \sin(\theta)\) |
| \(J = \Delta p\) | \(I = \sum mr^2\) |
| \(p_i = p_f\) | \(L = I \cdot \omega\) |
| Simple Harmonic Motion | Fluids |
|---|---|
| \(F = -kx\) | \(P = \frac{F}{A}\) |
| \(T = 2\pi \sqrt{\frac{l}{g}}\) | \(P_{\text{total}} = P_{\text{atm}} + \rho gh\) |
| \(T = 2\pi \sqrt{\frac{m}{k}}\) | \(Q = Av\) |
| \(x(t) = A \cos(\omega t + \phi)\) | \(F_b = \rho V g\) |
| \(a = -\omega^2 x\) | \(A_1v_1 = A_2v_2\) |
| Constant | Description |
|---|---|
| [katex]g[/katex] | Acceleration due to gravity, typically [katex]9.8 , \text{m/s}^2[/katex] on Earth’s surface |
| [katex]G[/katex] | Universal Gravitational Constant, [katex]6.674 \times 10^{-11} , \text{N} \cdot \text{m}^2/\text{kg}^2[/katex] |
| [katex]\mu_k[/katex] and [katex]\mu_s[/katex] | Coefficients of kinetic ([katex]\mu_k[/katex]) and static ([katex]\mu_s[/katex]) friction, dimensionless. Static friction ([katex]\mu_s[/katex]) is usually greater than kinetic friction ([katex]\mu_k[/katex]) as it resists the start of motion. |
| [katex]k[/katex] | Spring constant, in [katex]\text{N/m}[/katex] |
| [katex] M_E = 5.972 \times 10^{24} , \text{kg} [/katex] | Mass of the Earth |
| [katex] M_M = 7.348 \times 10^{22} , \text{kg} [/katex] | Mass of the Moon |
| [katex] M_M = 1.989 \times 10^{30} , \text{kg} [/katex] | Mass of the Sun |
| Variable | SI Unit |
|---|---|
| [katex]s[/katex] (Displacement) | [katex]\text{meters (m)}[/katex] |
| [katex]v[/katex] (Velocity) | [katex]\text{meters per second (m/s)}[/katex] |
| [katex]a[/katex] (Acceleration) | [katex]\text{meters per second squared (m/s}^2\text{)}[/katex] |
| [katex]t[/katex] (Time) | [katex]\text{seconds (s)}[/katex] |
| [katex]m[/katex] (Mass) | [katex]\text{kilograms (kg)}[/katex] |
| Variable | Derived SI Unit |
|---|---|
| [katex]F[/katex] (Force) | [katex]\text{newtons (N)}[/katex] |
| [katex]E[/katex], [katex]PE[/katex], [katex]KE[/katex] (Energy, Potential Energy, Kinetic Energy) | [katex]\text{joules (J)}[/katex] |
| [katex]P[/katex] (Power) | [katex]\text{watts (W)}[/katex] |
| [katex]p[/katex] (Momentum) | [katex]\text{kilogram meters per second (kgm/s)}[/katex] |
| [katex]\omega[/katex] (Angular Velocity) | [katex]\text{radians per second (rad/s)}[/katex] |
| [katex]\tau[/katex] (Torque) | [katex]\text{newton meters (Nm)}[/katex] |
| [katex]I[/katex] (Moment of Inertia) | [katex]\text{kilogram meter squared (kgm}^2\text{)}[/katex] |
| [katex]f[/katex] (Frequency) | [katex]\text{hertz (Hz)}[/katex] |
General Metric Conversion Chart
Example of using unit analysis: Convert 5 kilometers to millimeters.
Start with the given measurement: [katex]\text{5 km}[/katex]
Use the conversion factors for kilometers to meters and meters to millimeters: [katex]\text{5 km} \times \frac{10^3 \, \text{m}}{1 \, \text{km}} \times \frac{10^3 \, \text{mm}}{1 \, \text{m}}[/katex]
Perform the multiplication: [katex]\text{5 km} \times \frac{10^3 \, \text{m}}{1 \, \text{km}} \times \frac{10^3 \, \text{mm}}{1 \, \text{m}} = 5 \times 10^3 \times 10^3 \, \text{mm}[/katex]
Simplify to get the final answer: [katex]\boxed{5 \times 10^6 \, \text{mm}}[/katex]
Prefix | Symbol | Power of Ten | Equivalent |
|---|---|---|---|
Pico- | p | [katex]10^{-12}[/katex] | |
Nano- | n | [katex]10^{-9}[/katex] | |
Micro- | µ | [katex]10^{-6}[/katex] | |
Milli- | m | [katex]10^{-3}[/katex] | |
Centi- | c | [katex]10^{-2}[/katex] | |
Deci- | d | [katex]10^{-1}[/katex] | |
(Base unit) | – | [katex]10^{0}[/katex] | |
Deca- or Deka- | da | [katex]10^{1}[/katex] | |
Hecto- | h | [katex]10^{2}[/katex] | |
Kilo- | k | [katex]10^{3}[/katex] | |
Mega- | M | [katex]10^{6}[/katex] | |
Giga- | G | [katex]10^{9}[/katex] | |
Tera- | T | [katex]10^{12}[/katex] |
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