You are Here: Home >< Maths

# Maths Projectile. watch

1. An Object is projected vertically upwards from ground level and it's height, H metres, after t seconds is given by the formula:

Show that the object is above a height of 90 metres for about 8.5 seconds
working:

Then I used the quadratic formula and got 10.24

where have I gone wrong?
2. (Original post by joyoustele)
An Object is projected vertically upwards from ground level and it's height, H metres, after t seconds is given by the formula:

Show that the object is above a height of 90 metres for about 8.5 seconds
working:

Then I used the quadratic formula and got 10.24

where have I gone wrong?
You should get two (positive) roots whose difference is about 8.5 seconds.
3. (Original post by joyoustele)
An Object is projected vertically upwards from ground level and it's height, H metres, after t seconds is given by the formula:

Show that the object is above a height of 90 metres for about 8.5 seconds
working:

Then I used the quadratic formula and got 10.24

where have I gone wrong?
When you solve a quadratic equations with real roots you should get two solutions ...

### Related university courses

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:
Updated: November 10, 2017
Today on TSR

### 1,748

students online now

Exam discussions

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams