Concept explainers
Review Question 5.1 How do we know that the sum of the forces exerted on an object moving in a circle at constant speed points toward the center of the circle?
The validity of the statement that the sum of the forces exerted on a body in circular motion, moving with constant speed, acts toward the center of the circle.
Answer to Problem 1RQ
Solution:
Using the Newton’s second law of motion it can be validated that there is force along radial direction only.
Explanation of Solution
Given data:
The body is undergoing circular motion at a constant speed.
Formula used:
Write the expression for Newton’s second law of motion.
Here,
Explanation:
For a body undergoing circular motion at a constant speed, the direction of motion changes at every instance of time. So the velocity, being a vector quantity, changes at every instant of time.
Also, the change in velocity in a circular motion gives rise to a radial acceleration. The direction of this radial acceleration is towards the center of the circle.
From Newton’s second law,
The net force is the function of acceleration of the body of mass
In case of uniform circular motion, the acceleration is the radial acceleration which acts in a direction towards the center of the circle. Hence, the net force acting in uniform circular motion with a constant speed also acts in the direction of the center of the circle.
Conclusion:
The net force acting on the body undergoing circular motion with a constant speed is a function of its acceleration which acts in a direction towards the center of circle of motion.
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