(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A parachutist of mass 65 kg jumps out of a plane deploys a chute.

When the chute opens, she slows down from 80km/h to 10km/h in 0.8s. What is the foce of the chute on her shoulders at that time?

m = 65 kg

v1 = 80km/h → 22 m/s

v2 = 10 km/h → 2.8 m/s

change in time = 0.8 s

2. Relevant equations

a = v/t

Fnet = ma

3. The attempt at a solution

We're assuming that up is positive.

I used to sig figs for all my values.

First we need to find the acceleration

a = v/t

a = (2.8 - 22)/0.8

a = -24 m/s^2

Let Fp = force of the parachute

Fnet = ma

Fg + Fp = ma

-640 + Fp = (65)(-24)

-640 + Fp = -1560

Fp = -1560 + 640

Fp = -920 N

I'm confused as to what I'm doing wrong. My teacher told us the answer should be about 2200 N and that would be positive while my answer is turning out completely off and negative.

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# Force of a parachute on parachutist

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