Math Problem Statement

A person with a mass of 60 kg jumps vertically in the air. They leave the ground with a speed of 3 m/s. Ignoring the effect of air resistance, calculate the maximum possible height that the person could reach. Give your answer to 2 significant figures. The gravitational field strength on Earth is 9.8 N/kg.

Solution

We can solve the problem by using the concept of conservation of energy or the kinematic equation for vertical motion.

Since air resistance is neglected, all the initial kinetic energy is converted into gravitational potential energy at the highest point of the jump.

Step 1: Use Energy Conservation

The formula for kinetic energy is: KE=12mv2KE = \frac{1}{2} m v^2 Where:

  • m=60kgm = 60 \, \text{kg} (mass of the person),
  • v=3m/sv = 3 \, \text{m/s} (initial speed when leaving the ground).

The gravitational potential energy (PE) at the maximum height hh is: PE=mghPE = mgh Where:

  • g=9.8m/s2g = 9.8 \, \text{m/s}^2 (gravitational acceleration),
  • hh is the height we want to calculate.

At the maximum height, the kinetic energy is fully converted to potential energy, so: 12mv2=mgh\frac{1}{2} m v^2 = mgh

Step 2: Simplify and Solve for hh

Cancel out the mass mm from both sides: 12v2=gh\frac{1}{2} v^2 = gh Now, solve for hh: h=v22gh = \frac{v^2}{2g}

Step 3: Substitute the values

h=(3)22×9.8=919.6h = \frac{(3)^2}{2 \times 9.8} = \frac{9}{19.6} h=0.46mh = 0.46 \, \text{m}

Answer:

The maximum height the person can reach is 0.46 meters (rounded to 2 significant figures).


Would you like further details or have any other questions? Here are 5 related questions for practice:

  1. How would air resistance affect the height the person can reach?
  2. What if the person left the ground with a speed of 4 m/s? How would that change the result?
  3. How does the gravitational field strength affect the maximum height?
  4. What is the maximum height a person can reach on the Moon, where g=1.62m/s2g = 1.62 \, \text{m/s}^2?
  5. How much kinetic energy does the person have initially?

Tip: When solving physics problems involving energy, always consider whether external forces like friction or air resistance need to be taken into account.

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Math Problem Analysis

Mathematical Concepts

Conservation of Energy
Kinematics
Potential Energy
Kinetic Energy

Formulas

Kinetic Energy: KE = 1/2 m v^2
Potential Energy: PE = mgh
Height formula: h = v^2 / 2g

Theorems

Conservation of Mechanical Energy

Suitable Grade Level

Grades 9-12