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Grade 12th passMechanics

An unstretched ring has a bead attached to one end and a block at other end and is passing through smooth pulley as shown in figure .The speed of bead at the instant given in the figure is?(Sir,I just have a little doubt.Here which is correct vcos 60=5 or 5cos60=v and why how can we identify it?)

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Profile image of Kaushki
7 Years agoGrade 12th pass
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1 Answer

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ApprovedApproved Tutor Answer11 Months ago

To address your question about the relationship between the speed of the bead and the geometry of the setup, let's break it down step by step. The scenario involves a bead on a ring and a block, with the ring passing over a smooth pulley. The angle mentioned, 60 degrees, plays a crucial role in determining the components of the velocity of the bead.

Understanding the Components of Velocity

When dealing with problems involving angles and velocities, it's essential to analyze the components of the velocity vector. In this case, we have a bead moving along a circular path, and we want to relate its speed to the angle of motion.

Identifying the Correct Equation

You're considering two expressions: v cos(60°) = 5 and 5 cos(60°) = v. To determine which is correct, we need to clarify what each term represents:

  • v is the speed of the bead.
  • 5 is a constant that likely represents a distance or a specific component of motion.
  • cos(60°) is a trigonometric function that equals 0.5.

Now, let's analyze both equations:

Breaking Down the Equations

1. **For the equation v cos(60°) = 5**:

  • Substituting cos(60°) = 0.5, we get v * 0.5 = 5.
  • This simplifies to v = 10.

2. **For the equation 5 cos(60°) = v**:

  • Again substituting cos(60°) = 0.5, we have 5 * 0.5 = v.
  • This simplifies to v = 2.5.

Determining the Correct Expression

To identify which equation is correct, consider the context of the problem. If the bead is moving along the ring and the distance of 5 is related to the vertical component of the bead's motion, then the first equation, v cos(60°) = 5, is likely the correct one. This is because it indicates that the vertical component of the bead's velocity is equal to 5, which is consistent with the geometry of the setup.

Visualizing the Scenario

Imagine the bead moving in a circular path. The angle of 60 degrees indicates that the bead's motion can be decomposed into vertical and horizontal components. The vertical component (which we set equal to 5) is influenced by the angle, while the total speed (v) is what we want to find. Thus, the relationship v cos(60°) = 5 accurately reflects the situation.

Final Thoughts

In summary, the correct expression is v cos(60°) = 5, leading to a speed of v = 10. This approach of breaking down the velocity into components using trigonometric functions is a powerful tool in physics, especially in problems involving angles and motion. If you have any further questions or need clarification on any part of this, feel free to ask!