Math Problem Statement

A 300 g block on a 58.0-cm-long string swings in a circle on a horizontal, frictionless table at 95.0 rpm. What is the speed of the block?

Solution

To determine the speed of the block swinging in a circle, we'll use the relationship between circular motion and speed.

Given:

  • Mass of the block, m=300g=0.300kgm = 300 \, \text{g} = 0.300 \, \text{kg}
  • Length of the string (radius of the circle), r=58.0cm=0.580mr = 58.0 \, \text{cm} = 0.580 \, \text{m}
  • Rotation speed, f=95.0rpmf = 95.0 \, \text{rpm}

Required:

  • Speed of the block, vv

Step 1: Convert rpm to rad/s

The speed of the block depends on the angular velocity, which is related to the frequency (in revolutions per minute, rpm). We need to convert the angular velocity to radians per second (ω\omega):

ω=2πf\omega = 2 \pi f

where:

  • f=95.0rpm60s/min=1.5833rpsf = \frac{95.0 \, \text{rpm}}{60 \, \text{s/min}} = 1.5833 \, \text{rps} (revolutions per second)

ω=2π×1.58339.948rad/s\omega = 2 \pi \times 1.5833 \approx 9.948 \, \text{rad/s}

Step 2: Find the linear speed vv

The linear speed vv is related to the angular speed ω\omega and the radius rr:

v=ωrv = \omega r

Substitute the values:

v=9.948rad/s×0.580mv = 9.948 \, \text{rad/s} \times 0.580 \, \text{m}

v5.77m/sv \approx 5.77 \, \text{m/s}

Final Answer:

The speed of the block is approximately 5.77 m/s.

Would you like more details on how circular motion equations are derived or any other part of the solution?

Here are some related questions for further practice:

  1. What is the centripetal force acting on the block in this problem?
  2. How would the speed change if the string length doubled?
  3. What would happen to the speed if the mass of the block was increased?
  4. How does friction affect the motion if the surface is not frictionless?
  5. How would you calculate the tension in the string during circular motion?

Tip: Remember, in uniform circular motion, the speed remains constant, but the direction changes continuously, leading to centripetal acceleration.

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Math Problem Analysis

Mathematical Concepts

Circular Motion
Angular Velocity
Linear Speed

Formulas

Angular Velocity (ω) = 2πf
Linear Speed (v) = ωr

Theorems

Uniform Circular Motion Theorem

Suitable Grade Level

Grades 11-12