A particle is projected vertically upwards from a point O with initial speed 12.5 m s−1. At the same instant another particle is released from rest at a point 10 m vertically above O. Find the height above O at which the particles meet.?

1 Answer
Apr 9, 2018

The height is =6.86m

Explanation:

The acceleration due to gravity is g=9.8ms2

The height where the particles will meet is =lm

The distance travelled by the particle from the bottom is =lm

The distance travelled by particle from the top is =(10l)m

Apply the equation of motion,

s=ut+12at2

The time when they will meet is =ts

For the particle from the bottom

l=12.5×t12×9.8×t2

For the particle from the top

10l=0×t+12×9.8×t2

Therefore,

10(12.5×t12×9.8×t2)=0×t+12×9.8×t2

1012.5×t+12×9.8×t2=0×t+12×9.8×t2

1012.5t=0

t=1012.5=0.8s

So,

l=12.50.84.90.82=6.86m