Zeen asks:

A boy jumps from rest, straight down from the top of a cliff. He falls halfway down to the water below in 0.800 s. How much time passes during his entire trip from the top down to the water? Ignore air resistance.

**Answer **:

let the total height be h

So, **for first case**

S = h/2

a = g=10 m/s^2

u=0 m/s

t = 0.8 sec

using the relation

h/2 = 0.5 x 10×0.8 ^2

h=6.4 m

**In second case (considering the full motion)**

S=h=6.4m

t=?

a=g=10m/s^2

u=o m/s

using the relation

6.4 = 0.5 x 10 x t^2

or

t = 2 x 6.4/10 = **1.28 s**

### Like this:

Like Loading...

*Related*

here we have to use Newton’s equations of motion.