Math Problem Statement

A 23.0 kg child is riding a playground merry-go-round that is rotating at 45.0 rpm. What centripetal force, in N, must she exert to stay on if she is 2.00 m from its center?

Solution

To find the centripetal force FcF_c that the child must exert to stay on the merry-go-round, we need to use the formula for centripetal force:

Fc=macF_c = m \cdot a_c

where:

  • mm is the mass of the child,
  • aca_c is the centripetal acceleration.

Step 1: Convert the Rotational Speed to Radians per Second

The given rotational speed is in revolutions per minute (rpm), so we need to convert it to radians per second.

  1. The merry-go-round rotates at 45.0rpm45.0 \, \text{rpm}.
  2. Convert rpm to revolutions per second: 45.0rpm60=0.75revolutions per second\frac{45.0 \, \text{rpm}}{60} = 0.75 \, \text{revolutions per second}
  3. Convert revolutions per second to radians per second, noting that one revolution is 2π2\pi radians: ω=0.75×2π=1.5π4.71rad/s\omega = 0.75 \times 2\pi = 1.5\pi \approx 4.71 \, \text{rad/s}

Step 2: Calculate Centripetal Acceleration aca_c

The centripetal acceleration is given by:

ac=ω2ra_c = \omega^2 \cdot r

where:

  • ω=4.71rad/s\omega = 4.71 \, \text{rad/s} (angular velocity),
  • r=2.00mr = 2.00 \, \text{m} (distance from the center).

Substitute the values:

ac=(4.71)2×2.0044.34m/s2a_c = (4.71)^2 \times 2.00 \approx 44.34 \, \text{m/s}^2

Step 3: Calculate Centripetal Force FcF_c

Now, use the mass of the child (m=23.0kgm = 23.0 \, \text{kg}) and the centripetal acceleration:

Fc=mac=23.0×44.341019.8NF_c = m \cdot a_c = 23.0 \times 44.34 \approx 1019.8 \, \text{N}

Answer

The centripetal force the child must exert to stay on the merry-go-round is approximately:

Fc1019.8NF_c \approx 1019.8 \, \text{N}

Would you like more details or have any questions?


Related Questions

  1. How would the centripetal force change if the child was closer to the center, say at 1.0 m?
  2. What happens to the centripetal force if the merry-go-round's speed increases?
  3. How is centripetal acceleration related to the radius and angular velocity?
  4. What would be the required force if the child’s mass increased to 30 kg?
  5. If the merry-go-round was rotating at 60 rpm, what would the new centripetal force be?

Tip

When dealing with rotational motion, always ensure to convert angular speeds to consistent units, typically radians per second for calculations in physics.

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Math Problem Analysis

Mathematical Concepts

Centripetal Force
Circular Motion
Angular Velocity Conversion

Formulas

Centripetal force formula: F_c = m * a_c
Angular velocity conversion: ω (rad/s) = rpm * 2π / 60
Centripetal acceleration formula: a_c = ω^2 * r

Theorems

Centripetal force in circular motion

Suitable Grade Level

Grades 10-12