Avi, a gymnast, weighs [tex]$40 \, \text{kg}$[/tex]. She is jumping on a trampoline that has a spring constant value of [tex]$176,400 \, \frac{N}{m}$[/tex]. If she compresses the trampoline [tex][tex]$20 \, \text{cm}$[/tex][/tex], how high should she reach?

[tex]\square \, \text{meters}[/tex]



Answer :

First, let's understand the problem:

- Avi weighs 40 kg.
- The spring constant of the trampoline is [tex]\(176,400 \frac{N}{m}\)[/tex].
- Avi compresses the trampoline by [tex]\(20 \text{ cm}\)[/tex], which is [tex]\(0.20 \text{ meters}\)[/tex].

To find out how high Avi should reach, we follow these steps:

1. Calculate the Potential Energy (PE) stored in the compressed trampoline:

The potential energy stored in a compressed spring is given by the formula:
[tex]\[ PE = \frac{1}{2} k x^2 \][/tex]
where [tex]\(k\)[/tex] is the spring constant and [tex]\(x\)[/tex] is the compression distance.

Plugging in the values:
[tex]\[ PE = \frac{1}{2} \times 176,400 \frac{N}{m} \times (0.20 \text{ m})^2 \][/tex]
[tex]\[ PE = \frac{1}{2} \times 176,400 \times 0.04 \][/tex]
[tex]\[ PE = 3,528 \text{ Joules} \][/tex]

2. Convert Avi's weight to force:

The force due to gravity on Avi can be calculated as:
[tex]\[ F = m \times g \][/tex]
where [tex]\(m\)[/tex] is Avi's mass (40 kg) and [tex]\(g\)[/tex] is the acceleration due to gravity, which is [tex]\(9.81 \frac{m}{s^2}\)[/tex].

[tex]\[ F = 40 \text{ kg} \times 9.81 \frac{m}{s^2} \][/tex]
[tex]\[ F = 392.4 \text{ Newtons} \][/tex]

3. Determine the height (h) she should reach:

The potential energy converted to gravitational potential energy when she reaches a height [tex]\(h\)[/tex] is given by:
[tex]\[ PE = m \times g \times h \][/tex]

We know the potential energy (3,528 Joules) and the force (392.4 Newtons), hence:
[tex]\[ 3,528 = 392.4 \times h \][/tex]

Solving for [tex]\(h\)[/tex]:
[tex]\[ h = \frac{3,528}{392.4} \][/tex]
[tex]\[ h \approx 8.99 \text{ meters} \][/tex]

Therefore, Avi should reach approximately [tex]\(8.99 \text{ meters}\)[/tex] high.