Question

a particle is projected horizontally from the top of a building of height 20 m with speed 30 metre per second. distance of point where particle lands on ground from its point of projection is

Answer 1

Explanation:

20root10 is the correct answer

Answer 2

Given:

Height of the building = 20m

Initial horizontal speed = 30m/s

To find:

Distance of point where particle lands on ground from its point of projection.

Solution:

Let the point where the particle lands be r

Horizontal velocity: v= r/t

t = time of free fall from a height of 20m, as initial velocity in vertical direction=0, and we know that:

S = ut + 1/2at^2

20 = 1/2 * 10* t^2

t = 2 sec

Putting the value of t in the equation we get:

v = r/t

30 = r/ 2

r = 60m, this is the horizontal distance.

Since, the particle was projected from top of the building, the vertical distance = 20m

Total distance of the particle from the point of projection:

((60)^2 + (20)^2) ^1/2

= 63.25 m

Therefore, the distance of point where the particle lands on ground from its point of projection is 63.25m.