Falling objects drop with an average acceleration of 9.8 m/s2. If an object falls from a tall building, how long will it take before it reaches a speed of 63.7 m/s?

Question

a = vf – vi vf = vi + at t = vf-vi

           t     a   

My teacher gave me these formulas and im not sure which one it is or even how to do this.

Find the Average acceleration.

Answer 1

You use the second equation vf=vi+at

It is released from rest so vi=o, we know vf = 63.7 and g = 9.8

We now have 63.7 = 9.8 t

So t = 63.7/9.8

It therefore takes 6.5 seconds