Math Is Fun Forum

Karn

Member

Registered: 2009-11-15

Posts: 14

Factorisation

Hi

I am stuck on this question

1) When an object is projected upwards from ground level, with initial speed 40 m/s, the height it is above ground t seconds later is h metres where h is given by:           h ≈ 40t - 5t^2
State the value of h when the object hits the ground again and find the value of t then.

Thank you

Last edited by Karn (2009-12-30 22:17:06)

Identity

Member

Registered: 2007-04-18

Posts: 934

Re: Factorisation

When the object hits the ground again h = 0.

To find the value of t at that time, solve:

But when t = 0 represents the time it is launched, so the value of t when it lands is 8.