Hey! Sign in to get help with your study questionsNew here? Join for free to post
 You are Here: Home >< Maths

# Direct proportion question

Announcements Posted on
Why bother with a post grad? Are they even worth it? Have your say! 26-10-2016
1. A ball falls vertically after being dropped. The ball falls a distance, d metres, in a time of t seconds.
d is directly proportional to the square of t.

I worked out the first question which was the formula:

Another question was, calculate the time the ball takes to fall 605m

So i did

That was the final answer, however i was wondering, do i not divide by 5 to get t on its own?

If not for this one, do i ever? Or do you leave a number next to it always?

Thank you!
2. did you not divide by 5 to get from 605 to 121
3. (Original post by TenOfThem)
did you not divide by 5 to get from 605 to 121

Aaah right yeh! So it would just be

then Sqrt that? :O?
4. yup
5. (Original post by DeathByBSOD)
My Maths is kinda rusty, :s

so i think its:

Therefore,
~ 4.92s
This is incorrect ... the OP now has the correct answer
6. (Original post by DeathByBSOD)
My Maths is kinda rusty, :s but where did you get the 5 FROM?

so i think its:

Therefore,

the 5 is from the first part of the question, when 20 is directly proportion to 4k so k=5
7. (Original post by IgorYakov)
the 5 is from the first part of the question, when 20 is directly proportion to 4k so k=5

Ah Ok thanks.

Write a reply…

Submit reply

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
that username has been taken, please choose another Forgotten your password?
2. this can't be left blank
this email is already registered. Forgotten your password?
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
your full birthday is required
1. Oops, you need to agree to our Ts&Cs to register
2. Slide to join now Processing…

Updated: April 19, 2012
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

### Who is getting a uni offer this half term?

Find out which unis are hot off the mark here

Poll
Useful resources

## Make your revision easier

### Maths Forum posting guidelines

Not sure where to post? Read here first

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams

Can you help? Study help unanswered threads

## Groups associated with this forum:

View associated groups
Study resources

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.