Question

76. 10 An object falls from the top of a building that is 25 m high. Air resistance is negligible What is the speed of the object when it hits the ground? A 10 m/s B 22 mis C 25 m/s D 625 mis C D​

Answer 1

According to the question:
Initial velocity (u)=0
Height of the building (h)=25m
Acceleration due to gravity (g)=10m/s
Final velocity (v)=?
v ²+u ²=2gh
v ²=2gh [as initial velocity is 0]
v= √2gh
= √2*10*25
= √500
= √5* √100
= √5*10
=2.236*10
=22.36m/s ≈ 22m/s (B)

Answer 2

Given: An object falls from the top of a building that is 25 m high.

To find: The speed of the object when it hits the ground.

Solution:

• The equation of a body that is falling freely from a height can be calculated using the formula,

        $v^{2} - u^{2} = 2gS$

• Here, v is the final velocity, u is the initial velocity, g is the acceleration due to gravity and S is the distance traveled by the object.
• Since the object falls freely, its initial velocity would be zero.

        $v^{2} - 0^{2} = 2(10ms^{-2})(25m)$

        $v = 22.36 ms^{-1}$

Therefore, the final velocity of the object is 22.36 ms⁻¹.