## anonymous 5 years ago On the moon the acceleration due to gravity is 1.6 metres per second squared (approximately 1 6 th of the value on earth). Standing on top of a ladder, 5 metres up, the astronaut throws a ball up vertically into the air with velocity 2m/s. How long does it take to reach the ground? How long would it take to reach the ground if the same experiment were done on earth?

1. anonymous

2. anonymous

lol

3. anonymous

THAT DOESN'T HELP!

4. anonymous

I have an answer, but I am not entirely sure if it's correct or not. I'll write it down anyway.

5. anonymous

go for it

6. anonymous

$\Delta x=v_i t+{1 \over 2}at^2$, where delta x=-5 (the change in the position), v_i=2m/s and a=-1.6m/s^2. Substituting them in the equation gives: $-5=2t+{1 \over 2}(-1.6)t^2 \implies 0.8t^2-2t-5=0$

7. anonymous

Solve the quadratic equation for t, you get one positive value for t. That's t=4.05 sec

8. anonymous

Do you have the answer, or choices?

9. anonymous

i only got to having to use the quadratic equation, i didn't realise i had to use the quadratic equation

10. anonymous

You can just do it in your calculator.

11. anonymous

yeah i just had to recognise that cause i think i'm meant to show working

12. anonymous

13. anonymous

yeah, cause i m having maximum trouble with it :)

14. anonymous

LOL!