13. A 700-kg horse whose power output is 1.0 hp is pulling a sled over the snow at 3.5 m/s. Find the force the horse exerts on the sled.

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ISBN:9781305952300
Author:Raymond A. Serway, Chris Vuille
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Chapter1: Units, Trigonometry. And Vectors
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Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...
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### Physics Problem: Calculating the Speed of a Car
#### Problem Statement
**Question 18:** What is the speed of an 800-kg car whose kinetic energy (KE) is 250 kJ?

#### Detailed Explanation
To solve this problem, we need to use the formula for kinetic energy: 
\[ KE = \frac{1}{2}mv^2 \]

Where:
- \( KE \) is the kinetic energy
- \( m \) is the mass of the object
- \( v \) is the velocity (or speed) of the object

Given:
- \( KE = 250 \text{kJ} = 250,000 \text{J} \)
- \( m = 800 \text{kg} \)

We need to find the speed \( v \).

#### Step-by-Step Solution
1. **Start with the kinetic energy formula:**
\[ KE = \frac{1}{2}mv^2 \]

2. **Rearrange the formula to solve for \( v \):**
\[ v^2 = \frac{2 \cdot KE}{m} \]
\[ v = \sqrt{\frac{2 \cdot KE}{m}} \]

3. **Substitute the given values into the formula:**
\[ v = \sqrt{\frac{2 \cdot 250,000}{800}} \]

4. **Calculate the values step-by-step:**
\[ v = \sqrt{\frac{500,000}{800}} \]
\[ v = \sqrt{625} \]
\[ v = 25 \text{ m/s} \]

#### Final Answer
The speed of the 800-kg car with a kinetic energy of 250 kJ is **25 meters per second (m/s)**.
Transcribed Image Text:### Physics Problem: Calculating the Speed of a Car #### Problem Statement **Question 18:** What is the speed of an 800-kg car whose kinetic energy (KE) is 250 kJ? #### Detailed Explanation To solve this problem, we need to use the formula for kinetic energy: \[ KE = \frac{1}{2}mv^2 \] Where: - \( KE \) is the kinetic energy - \( m \) is the mass of the object - \( v \) is the velocity (or speed) of the object Given: - \( KE = 250 \text{kJ} = 250,000 \text{J} \) - \( m = 800 \text{kg} \) We need to find the speed \( v \). #### Step-by-Step Solution 1. **Start with the kinetic energy formula:** \[ KE = \frac{1}{2}mv^2 \] 2. **Rearrange the formula to solve for \( v \):** \[ v^2 = \frac{2 \cdot KE}{m} \] \[ v = \sqrt{\frac{2 \cdot KE}{m}} \] 3. **Substitute the given values into the formula:** \[ v = \sqrt{\frac{2 \cdot 250,000}{800}} \] 4. **Calculate the values step-by-step:** \[ v = \sqrt{\frac{500,000}{800}} \] \[ v = \sqrt{625} \] \[ v = 25 \text{ m/s} \] #### Final Answer The speed of the 800-kg car with a kinetic energy of 250 kJ is **25 meters per second (m/s)**.
**Problem 13**

**Question:**
A 700-kg horse, whose power output is 1.0 hp, is pulling a sled over the snow at 3.5 m/s. Find the force the horse exerts on the sled.

---

**Explanation:**
This problem involves calculating the force exerted by a horse while pulling a sled, given the horse's power output and the sled’s velocity. The relevant concepts include the relationship between power, force, and velocity.

---
**Solution:**

1. **Given Data:**
   - Mass of the horse (\( m \)) = 700 kg
   - Power output (\( P \)) = 1.0 hp (horsepower)
   - Speed of the sled (\( v \)) = 3.5 m/s

2. **Conversion of Units:**
   - 1 horsepower (hp) is equivalent to 745.7 watts (W).

   Thus, power in watts:
   \[ P = 1.0 \, \text{hp} \times 745.7 \, \frac{\text{W}}{\text{hp}} = 745.7 \, \text{W} \]

3. **Power Equation:**
   The formula to relate power, force, and velocity is given by:
   \[ P = F \times v \]
   Where:
   - \( P \) is the power,
   - \( F \) is the force,
   - \( v \) is the velocity.

4. **Calculate Force:**
   Rearrange the equation to solve for force (\( F \)):
   \[ F = \frac{P}{v} \]
   Plug in the given values:
   \[ F = \frac{745.7 \, \text{W}}{3.5 \, \text{m/s}} \approx 213 \, \text{N} \]

**Answer:**
The force the horse exerts on the sled is approximately 213 Newtons (N).

---

This solution incorporates the necessary steps to convert units, use the appropriate formula, and calculate the required force, making it suitable for educational purposes.
Transcribed Image Text:**Problem 13** **Question:** A 700-kg horse, whose power output is 1.0 hp, is pulling a sled over the snow at 3.5 m/s. Find the force the horse exerts on the sled. --- **Explanation:** This problem involves calculating the force exerted by a horse while pulling a sled, given the horse's power output and the sled’s velocity. The relevant concepts include the relationship between power, force, and velocity. --- **Solution:** 1. **Given Data:** - Mass of the horse (\( m \)) = 700 kg - Power output (\( P \)) = 1.0 hp (horsepower) - Speed of the sled (\( v \)) = 3.5 m/s 2. **Conversion of Units:** - 1 horsepower (hp) is equivalent to 745.7 watts (W). Thus, power in watts: \[ P = 1.0 \, \text{hp} \times 745.7 \, \frac{\text{W}}{\text{hp}} = 745.7 \, \text{W} \] 3. **Power Equation:** The formula to relate power, force, and velocity is given by: \[ P = F \times v \] Where: - \( P \) is the power, - \( F \) is the force, - \( v \) is the velocity. 4. **Calculate Force:** Rearrange the equation to solve for force (\( F \)): \[ F = \frac{P}{v} \] Plug in the given values: \[ F = \frac{745.7 \, \text{W}}{3.5 \, \text{m/s}} \approx 213 \, \text{N} \] **Answer:** The force the horse exerts on the sled is approximately 213 Newtons (N). --- This solution incorporates the necessary steps to convert units, use the appropriate formula, and calculate the required force, making it suitable for educational purposes.
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