Hello everyone. I am a 9th grade student in Massachusetts. I am currently taking Physics. For an assignment, we are sometimes given problems to do on an online-test site called Webassign. I am having a big problem on one of my questions. For this question, we are given 5 chances to get it right. I only have one chance left to get it right and I REALLY need your help since this is the difference between an 83 and a 92 for this assignment. The question is...

Calculate a person's hang time if he moves horizontally 4 m during a 1.23 m high-jump.

AND

What is his hang time if he moves 8 m horizontally during this jump?

This is a two part question. I have already gotten the first part incorrect and used up all of my submissions. But the second part I have one chance left.

I keep getting 0.501 seconds which the program is telling me incorrect. I am using the formula for hang time which I think is...

t= the square root of 2d/g

PLEASE SOME ONE HELP ME IT IS DUE IN ABOUT 3 HOURS!!!!

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## Answers and Replies

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Hootenanny
Staff Emeritus
Gold Member
Hi omiz and welcome to the forums,

For future reference there are Homework Forums specifically for answering such questions. Now to your question. The formula you are using is almost, but not quite correct. Can I ask how you obtained this equation?

Oops...sorry I did not know there was a homework help forum.

I attained the formula from my physics book

Conceptual Physics: tenth edition

It is one of Paul G. Hewitt's books.

Are you going to help me on this problem or should I go to the H/W forums?

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## Homework Statement

Calculate a person's hang time if he moves horizontally 4 m during a 1.23 m high-jump. What is his hang time if he moves 8 m horizontally during this jump?

## Homework Equations

I need to know the correct formula for hang time!

## The Attempt at a Solution

I have tried and tried and I keep getting 0.501 seconds! I am using a program called Webassign for homework and I only have one more chance to get this problem right! Please Help!

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Gokul43201
Staff Emeritus
Gold Member
There isn't a "formula for hang time". Show us what you tried, so we can tell you what's wrong with it.

My physics book, "Conceptual Physics: tenth edition" says the formula for hang time is...

t = the square root of 2d/g

The only problem is which d to use. I have two d's in both cases. However I am fairly sure I am supposed to use 1.23m as the d since the horizontal distance shouldn't matter.

Perpendicular vectors are independent of each other, youve got that right. Youre supposed to use the distance thats in the direction of acceleration, so all thats left is to plug 1.23 in

I think I figured it out. In order to get the hang time, I need to multiply my answer, 0.501 by 2. I was only calculating the hang time for the jump up, and not for the entire trip.

By "hang time" do you mean the time it takes for your object to fall?