Math Problem Statement

A person stands at rest on a slope which makes an angle 16 degrees to the horizontal. They have a mass of 73 kg. They start to run up the slope. After a time of 7.4 s they reach a distance 23 m up the slope and have a velocity of 3.0 m/s.

(c) Calculate the average power output of the person.

Solution

To calculate the average power output of the person as they run up the slope, we need to determine the work done and the time taken.

Here's the approach we'll take:

  1. Calculate the Change in Potential Energy (PE): Since the person moves up the slope, there's an increase in gravitational potential energy.

    • Mass, m=73kgm = 73 \, \text{kg}
    • Distance along the slope, d=23md = 23 \, \text{m}
    • Angle of slope, θ=16\theta = 16^\circ
    • Gravitational acceleration, g=9.81m/s2g = 9.81 \, \text{m/s}^2

    The vertical height hh gained is: h=dsinθ=23sin(16)h = d \sin \theta = 23 \cdot \sin(16^\circ)

    Now calculate the change in potential energy: ΔPE=mgh\Delta \text{PE} = m \cdot g \cdot h

  2. Calculate the Change in Kinetic Energy (KE): The person starts from rest and reaches a final velocity of v=3.0m/sv = 3.0 \, \text{m/s}. ΔKE=12mv2\Delta \text{KE} = \frac{1}{2} m v^2

  3. Total Work Done: The work done WW is the sum of the changes in potential and kinetic energy: W=ΔPE+ΔKEW = \Delta \text{PE} + \Delta \text{KE}

  4. Calculate the Average Power Output: Power PP is the work done over time t=7.4st = 7.4 \, \text{s}: P=WtP = \frac{W}{t}

Solution

Let's go through the calculations step-by-step.

  1. Calculate hh: h=23sin(16)6.34mh = 23 \cdot \sin(16^\circ) \approx 6.34 \, \text{m}

  2. Calculate ΔPE\Delta \text{PE}: [ \Delta \text{PE} = 73 \cdot 9.81 \cdot 6.34 \approx

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Math Problem Analysis

Mathematical Concepts

Physics
Work and Energy
Trigonometry

Formulas

Potential Energy (PE) = m * g * h
Kinetic Energy (KE) = (1/2) * m * v^2
Total Work Done (W) = ΔPE + ΔKE
Average Power (P) = W / t
Height (h) = d * sin(θ)

Theorems

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Suitable Grade Level

Grade 11-12