Question

A knight sits on a castle wall during a siege. To while away the time, he notes that boulders catapulted from below land on the top of his wall with a vertical velocity of 5.6 m/s. If he is 39 m above the catapult, what is the initial velocity of the boulders? The acceleration of gravity is 9.8 m/s 2 . Answer in units of m/s.

Answer 1

v = 28.21 m/s

Step-by-step explanation:

given,

vertical velocity of the boulder = 5.6 m/s

height of catapult = 39 m

initial velocity = ?

acceleration due to gravity = 9.8 m/s²

maximum height attained

v² = u² + 2 as

5.6² = = 2 g h

`h = (5.6^2)/(2* 9.8)`

h = 1.6 m

total height above catapulted

H = 39 + 1.6 = 40.6 m

`v = √(2gh)`

`v = √(2* 9.8 * 40.6)`

v = 28.21 m/s

so the intial velocity is equal to v = 28.21 m/s