Question

A bird, accelerating from rest at a constant rate, experiences a displacement of 28 m in 11 s. what is the final velocity after 11 s?

Answer 1

Let's see what variables we've got first. Hmmm. We have:

Displacement, d = 28 m
Time taken, t = 11 s
Initial velocity, u = 0 m/s (at rest)

And now we need to find the final velocity, v. Among the 4 (or 5) equations of motions, there's no equation that will let us simply plug in the values and give an answer sigh. But fear not! We'll do it in steps.

I'm going to pick one of the motion equation to find more information:

$d = ut + \frac{1}{2} a {t}^{2}$

I know everything except for a in this one, so I I'll use this! After plugging in values, I get a = 0.4628 m/s^2.

Now I'm going to use another motion equation that has v in it because that needs to be solved!

$v = u + at$

Now I know everything except dial velocity v. Nice!

v = 0 + (0.4628)(11)