Question

A ball is projected vertically upwards from the
ground. It takes 4 s to reach a point P still moving
upwards. If it takes 10 s further to reach to ground,
then height of point P is​

Answer 1

Given:

A ball is projected vertically upwards from the  ground. It takes 4 s to reach a point P still moving  upwards.

To find:

If it takes 10 s further to reach to ground,  then height of point P is​

Solution:

From given, we have,

A ball is projected vertically upwards from the  ground.

It takes 4 s to reach a point P still moving  upwards.

we use the formula,

x = ut + 1/2 at²

x = u (4) - 1/2 g (4)²

x = 4u - 8g ........(1)

It takes 10 s further to reach to ground,

2u/g = (10 + 4)

2u/g = 14

u = (14 × g)/2

u = (14 × 10)/2

u = 70 m/s.

using (1)

x = 4u - 8g

x = 4 (70) - 8 (10)

x = 280 - 80

x = 200 m

The height of point P is​ 200 m