Question 830 of 949
A car is traveling around a circular track with a radius of 50 meters at a constant speed of 20 meters per second. What is the centripetal force acting on the car if its mass is 800 kg?
- 1600 N
- 3200 N
- 400 N
- 2000 N
Correct Answer:
B
Explanation
To determine the centripetal force acting on a car traveling around a circular track, we can use the formula for centripetal force, which is given by:
\[
F_c = \frac{mv^2}{r}
\]
where:
- \( F_c \) is the centripetal force,
- \( m \) is the mass of the object (in this case, the car),
- \( v \) is the speed of the object,
- \( r \) is the radius of the circular path.
### Step-by-Step Calculation
1. **Identify the given values**:
- Mass of the car, \( m = 800 \, \text{kg} \)
- Speed of the car, \( v = 20 \, \text{m/s} \)
- Radius of the circular track, \( r = 50 \, \text{m} \)
2. **Substitute the values into the formula**:
\[
F_c = \frac{800 \, \text{kg} \times (20 \, \text{m/s})^2}{50 \, \text{m}}
\]
3. **Calculate \( v^2 \)**:
\[
(20 \, \text{m/s})^2 = 400 \, \text{m}^2/\text{s}^2
\]
4. **Multiply \( m \) and \( v^2 \)**:
\[
800 \, \text{kg} \times 400 \, \text{m}^2/\text{s}^2 = 320000 \, \text{kg} \cdot \text{m}^2/\text{s}^2
\]
5. **Divide by \( r \)**:
\[
F_c = \frac{320000 \, \text{kg} \cdot \text{m}^2/\text{s}^2}{50 \, \text{m}} = 6400 \, \text{N}
\]
### Correct Answer
The calculated centripetal force is **6400 N**, which does not match any of the provided options. However, if we consider the options given, it seems there might be a misunderstanding in the question or the options provided.
### Explanation of the Options
- **A. 1600 N**: This value is too low. It does not account for the mass and speed of the car correctly.
- **B. 3200 N**: This value is also incorrect based on our calculations. It seems to be a miscalculation or misinterpretation of the centripetal force formula.
- **C. 400 N**: This is significantly lower than what we calculated and does not reflect the mass and speed of the car.
- **D. 2000 N**: This is also incorrect as it does not match our calculations.
### Common Pitfalls
- **Forgetting to square the speed**: A common mistake is to forget that the speed must be squared in the centripetal force formula.
- **Misunderstanding the radius**: Ensure that the radius is in the same units as the other measurements (meters in this case).
- **Confusing centripetal force with other forces**: Remember that centripetal force is not a separate force but rather the net force required to keep an object moving in a circular path.
### Revision Summary
- The formula for centripetal force is \( F_c = \frac{mv^2}{r} \).
- Always square the speed when using the formula.
- Ensure all units are consistent (e.g., mass in kg, speed in m/s, radius in m).
- Double-check calculations to avoid common errors.
In conclusion, the correct centripetal force acting on the car, based on the provided values, is **6400 N**, which does not match the options given. This indicates a potential error in the options or the question itself.