Question

Interactive Solution 6.39 presents a model for solving this problem. A slingshot fires a pebble from the top of a building at a speed of 13.0 m/s. The building is 23.0 m tall. Ignoring air resistance, find the speed with which the pebble strikes the ground when the pebble is fired (a) horizontally, (b) vertically straight up, and (c) vertically straight down.

Answer 1

Given that

u = 13 m/s

h= 23 m

a) horizontally

We know that acceleration due top gravity is in vertical direction.

v²=u'²+ 2 g h ( u'= 0 )

v² = 2 x 9.81 x 23

v= 21.24 m/s ( vertical direction)

In the horizontal direction

u = 13 m/s

The resultant velocity

V²=v²+u²

V²=21.24²+13²

V= 24.91 m/s

(b) vertically straight up

u= 13 m/s

v²=u²+ 2 g h

v²=13²+ 2 x 9.81 x 23

v= 24.91 m./s

c)vertically straight down.

u= 13 m/s

v²=u²+ 2 g h

v²=13²+ 2 x 9.81 x 23

v= 24.91 m./s