Why does a person's weight appear to increase when they jump on a scale?

[get_physical]

Homework Statement

I just have a general question regarding scales and forces. I came across a question that when a boy jumps on his scale, the weight shown is actually greater than his actual weight. I have a hard time picturing this because when he jumps, he isn't actually on the scale anymore, so wouldn't the weight come down??

I understand the elevator questions, but just not this concept.

For reference, go to this link and it's #4.19 http://www.physics.oregonstate.edu/~tgiebult/COURSES/ph221H/221HCh04.pdf

 

[cepheid]

Homework Statement

I just have a general question regarding scales and forces. I came across a question that when a boy jumps on his scale, the weight shown is actually greater than his actual weight. I have a hard time picturing this because when he jumps, he isn't actually on the scale anymore, so wouldn't the weight come down??

I understand the elevator questions, but just not this concept.

For reference, go to this link and it's #4.19 http://www.physics.oregonstate.edu/~tgiebult/COURSES/ph221H/221HCh04.pdf

It's not after he leaves the scale that the reading shown increases. It's during the push off, when he is crouched and preparing to jump by pushing down on the scale using his leg muscles. What a scale actually measures is the normal force on it. Usually this is equal to your weight, but if you are pushing down harder than that, it will be larger.