# This should be simple...?

I'm taking a basic physics class after several years of not taking any kind of math or physics classes. This question should be incredibly simple, but I'm absolutely stuck for reasons I can't understand. I never had any problems with advanced math, but I'm stumped now.

how long would it take an object to fall 2 m? We can use 10m/s2.

I see time, acceleration, and distance being the variables, but for the life of me I can't put them together, and my book doesn't give me any help.

How do you work this out?

Relevance
• 9 years ago

Use s = ut + 1/2 at^2

where u = initial velocity = 0, a = acceleration = 10m/s^2, t = time in seconds s = distance in metres = 2m.

2 = 0 + 5t^2

2/5 = t^2

0.4 = t^2

0.632s = t

• 9 years ago

D = D(initial) + V(initial)*t + 0.5*a*t^2

Since V(initial) is zero and D(initial) is zero at the drop point, and the a is -10 m/s^2 (down is negative by convention), you end up with

-2 = -10*t^2

2/10 = 1/5 = t^2

t = sqrt(1/5)

Make sense?