Chapter 12: Homework Problems Sond Help Save & Exit
16
Required information
Part1or2 Problem 12.018 - Blocks connected by a pulley system
Block A has a mass of 70 kg, and block 8 has a mass of 14 kg. The coefficients of friction between all surfaces of contact
are pt, = 020 and py = 0.15
294
points
eBook
Hit
&
pr p
References
Problem 12.018.a - Acceleration of the block in the pulley system
If P= 0, determine the acceleration of block B. (Round the final answer to three decimal places.)
The acceleration of block Bis J mis” 1 25°.
Question:
Chapter 12: Homework Problems Sond Help Save & Exit
16
Required information
Part1or2 Problem 12.018 - Blocks connected by a pulley system
Block A has a mass of 70 kg, and block 8 has a mass of 14 kg. The coefficients of friction between all surfaces of contact
are pt, = 020 and py = 0.15
294
points
eBook
Hit
&
pr p
References
Problem 12.018.a - Acceleration of the block in the pulley system
If P= 0, determine the acceleration of block B. (Round the final answer to three decimal places.)
The acceleration of block Bis J mis” 1 25°.
This is AI generated Response.
Asked by: Satish Reddy
Created at: 2025-06-27 05:02:22
Final Answer:
RenderedRaw Text
Did you like this answer?
Let's break down the problem:
### **Given:**
- Mass of Block A (\(m_A\)) = 70 kg
- Mass of Block B (\(m_B\)) = 14 kg
- Coefficient of static friction (\(\mu_s\)) = 0.20
- Coefficient of kinetic friction (\(\mu_k\)) = 0.15
- Incline angle (\(\theta\)) = 25°
- \(P = 0\) (no applied force)
### **Required:**
Find the acceleration of block B (\(a_B\)).
---
## **Step 1: Forces on Block A (along the incline)**
Block A is on an incline:
- Gravity component down the incline: \(m_A g \sin\theta\)
- Normal force: \(N = m_A g \cos\theta\)
- Friction force: \(F_{friction} = \mu_k N\)
- Tension in the rope: \(T\) (up the incline)
Eq. of motion for Block A (up the incline as positive):
\[
m_A a = T - m_A g \sin\theta - F_{friction}
\]
But friction opposes motion:
\[
F_{friction} = \mu_k m_A g \cos\theta
\]
So,
\[
m_A a = T - m_A g \sin\theta - \mu_k m_A g \cos\theta
\]
---
## **Step 2: Forces on Block B (vertical)**
Block B is hanging:
- Gravity: \(m_B g\)
- Tension: \(T\)
Eq. of motion for Block B (down is positive):
\[
m_B a = m_B g - T
\]
---
## **Step 3: Combine Equations**
Add the two equations (eliminate \(T\)):
\[
m_A a + m_B a = m_B g - [m_A g \sin\theta + \mu_k m_A g \cos\theta]
\]
\[
(m_A + m_B)a = m_B g - m_A g \sin\theta - \mu_k m_A g \cos\theta
\]
\[
a = \frac{m_B g - m_A g \sin\theta - \mu_k m_A g \cos\theta}{m_A + m_B}
\]
---
## **Step 4: Plug in Values**
- \(m_A = 70 \, \text{kg}\)
- \(m_B = 14 \, \text{kg}\)
- \(\mu_k = 0.15\)
- \(g = 9.81 \, \text{m/s}^2\)
- \(\sin 25^\circ \approx 0.4226\)
- \(\cos 25^\circ \approx 0.9063\)
Plug in:
\[
a = \frac{14 \times 9.81 - 70 \times 9.81 \times 0.4226 - 0.15 \times 70 \times 9.81 \times 0.9063}{70 + 14}
\]
Calculate each term:
- \(14 \times 9.81 = 137.34\)
- \(70 \times 9.81 \times 0.4226 \approx 289.97\)
- \(0.15 \times 70 \times 9.81 \times 0.9063 \approx 93.47\)
- \(70 + 14 = 84\)
Now combine:
\[
a = \frac{137.34 - 289.97 - 93.47}{84}
\]
\[
a = \frac{137.34 - 383.44}{84}
\]
\[
a = \frac{-246.10}{84}
\]
\[
a \approx -2.93 \, \text{m/s}^2
\]
---
### **Final Answer:**
\[
\boxed{-2.93 \ \text{m/s}^2}
\]
(The negative sign indicates the direction opposite the assumed positive, so block B accelerates **upward** relative to the direction we chose as positive for B.)
Question:
generate diagram
This is AI generated Response.
Asked by: Satish Reddy
Created at: 2025-06-27 05:03:30
VIPSolutions focuses on clear, step‑by‑step explanations so you can learn quickly. Whether you need an AI‑generated walkthrough or a short hint to get unstuck, each solution is organized for fast reading and easy review later.
Search similar questions, compare approaches, and bookmark the best answers for revision. Our goal is simple: quick, reliable study help that feels natural—not noisy.