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Question 419 of 949

What is the primary factor that determines the magnitude of the centripetal force acting on an object moving in a circular path?

  • The mass of the object and the radius of the circular path
  • The speed of the object and the gravitational force acting on it
  • The angular velocity and the distance from the center of rotation
  • The temperature of the object and the frictional force acting on it

Correct Answer: A

Explanation
**Correct Option: A. The mass of the object and the radius of the circular path** ### Detailed Explanation: Centripetal force is the force that keeps an object moving in a circular path. It acts towards the center of the circle around which the object is moving. The magnitude of the centripetal force (\(F_c\)) can be calculated using the formula: \[ F_c = \frac{mv^2}{r} \] Where: - \(F_c\) is the centripetal force, - \(m\) is the mass of the object, - \(v\) is the linear speed of the object, - \(r\) is the radius of the circular path. #### Step-by-Step Breakdown: 1. **Understanding the Formula**: - The formula shows that the centripetal force is directly proportional to the mass of the object (\(m\)) and the square of its speed (\(v^2\)), and inversely proportional to the radius of the circular path (\(r\)). - This means that if you increase the mass of the object or its speed, the centripetal force required to keep it moving in a circle increases. Conversely, if the radius of the circle increases, the required centripetal force decreases. 2. **Mass of the Object**: - The greater the mass of the object, the more force is needed to keep it moving in a circular path. This is because a heavier object has more inertia, which is the tendency of an object to resist changes in its state of motion. 3. **Radius of the Circular Path**: - A smaller radius means that the object is moving in a tighter circle, which requires a greater centripetal force to maintain that circular motion. If the radius increases, the object can move in a larger circle with less force needed to keep it in motion. 4. **Speed of the Object**: - The speed of the object is squared in the formula, indicating that even a small increase in speed results in a significant increase in the required centripetal force. For example, if the speed doubles, the required centripetal force increases by a factor of four. ### Why Other Options Are Incorrect: **B. The speed of the object and the gravitational force acting on it**: - While speed is indeed a factor in determining centripetal force, gravitational force does not directly influence the centripetal force in uniform circular motion unless the motion is occurring in a gravitational field (like a satellite orbiting Earth). In that case, gravitational force provides the centripetal force, but it is not a primary factor in the general formula for centripetal force. **C. The angular velocity and the distance from the center of rotation**: - Angular velocity is related to linear speed, but it is not a direct factor in the centripetal force formula. The distance from the center of rotation (radius) is relevant, but the option does not mention mass, which is crucial for determining the magnitude of the centripetal force. **D. The temperature of the object and the frictional force acting on it**: - Temperature does not affect the centripetal force directly. Frictional force can play a role in circular motion (like in a car turning on a road), but it is not a primary factor in the calculation of centripetal force itself. The centripetal force is a net force that can be provided by various forces, including friction, but it is not determined by them. ### Common Pitfalls: - Confusing centripetal force with other forces like gravitational force or frictional force. - Forgetting that the speed is squared in the centripetal force formula, which can lead to underestimating the force required for higher speeds. - Not recognizing that the radius of the circular path is inversely related to the centripetal force. ### Revision Summary: - Centripetal force is determined by the formula \(F_c = \frac{mv^2}{r}\). - Key factors include the mass of the object and the radius of the circular path. - Speed significantly affects the required centripetal force due to its squared relationship. - Gravitational force, angular velocity, temperature, and friction are not primary factors in the basic centripetal force equation.
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