Finding Time If you know Accel, Vi and distance

[student54321]

Homework Statement

Some aircraft are capable of accelerations
of magnitude 42.5 m/s2. If an aircraft starts
from rest, how long will it take the aircraft
to travel down the 2.6-km runway?

Homework Equations

d= vi(t) - 1/2 a(t)²

I am assuming that you need to solve for t. I had trouble altering the equation to do that.

The Attempt at a Solution

since velocity initial is 0m/s, I keep getting divide by zero error, and I get a cube root.

 

[cepheid]

Welcome to PF student54321,

Divide by zero error?

If v_i = 0, then v_it = 0, and the equation becomes:

d= 0 + (1/2)at²

Note that the second term should have a + sign, not a - sign, although typically 'a' also has an intrinsic sign depending on whether the acceleration is positive or negative.

This becomes:

d= (1/2)at²

Now can you solve for t?