In uniform circular motion, which of the following are constant: Check all that apply. speed velocity angular velocity centripetal acceleration magnitude of the net force
The Correct Answer and Explanation is:
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Correct Answers (Check all that apply):
✅ Speed
✅ Angular velocity
❌ Velocity
❌ Centripetal acceleration
✅ Magnitude of the net force
Explanation
In uniform circular motion, an object moves in a circular path with constant speed, but since its direction continuously changes, its velocity is not constant. Let’s break down each quantity:
✅ Speed – Constant
Speed is the scalar measure of how fast an object moves, regardless of direction. In uniform circular motion, the object travels equal distances in equal intervals of time around the circle, so speed remains constant.
❌ Velocity – Not Constant
Velocity is a vector that includes both magnitude (speed) and direction. Although the speed is constant, the direction of motion changes continuously as the object moves around the circle. Therefore, the velocity vector changes at every instant.
✅ Angular Velocity – Constant
Angular velocity is the rate at which the angle changes with time, measured in radians per second. In uniform circular motion, the object sweeps out equal angles in equal times, so the angular velocity remains constant.
❌ Centripetal Acceleration – Not Constant (in direction)
While the magnitude of centripetal acceleration (given by ac=v2ra_c = \frac{v^2}{r}ac=rv2) is constant (since speed and radius are constant), the direction of this acceleration constantly changes—it always points toward the center of the circle. Hence, centripetal acceleration as a vector is not constant.
✅ Magnitude of the Net Force – Constant
The net force acting on the object is the centripetal force, which has a constant magnitude of F=mv2rF = \frac{mv^2}{r}F=rmv2. Though the direction changes (always toward the center), its magnitude remains constant.
Summary:
- Constant: Speed, Angular Velocity, Magnitude of Net Force
- Not Constant: Velocity, Centripetal Acceleration (as vectors)
