a ball of mass 2 kg is projected horizontally with velocity 20m/s from a building of beight 15 m . The speed with which body hits the ground is -
Plzz show full method
Answers
Hi,
Answer: 10√7 m/s or 26.45 m/s
Explanation:
Given data:
The mass of the ball, m = 2 kg
The velocity with which the ball is projected, u = 20 m/s
The height of the building = 15 m
To find: The speed with which ball hits the ground
Solution:
We can solve the above question by using Newton’s law of gravitation & work energy theorem which is as follows:
Method (I): Using The Newton’s Law of Gravitation
Here,
The initial velocity, u = 20 m/s
The displacement, h = 15 m
The gravitational acceleration, g = 10 m/s²
Let the final velocity of the ball be “v” m/s.
Using the gravitational equation of motion,
v² = u² + 2gh
substituting the given values,
⇒ v² = 20² + 2(10)(15)
⇒ v² = 400 + 300
⇒ v = √700
⇒ v = 10√7 m/s or 26.45 m/s
Method (II): Using The Work-Energy Theorem
We know that,
Work done = Change in Kinetic energy
Therefore,
mgh = ½ m (v² - u²)
substituting the same given values in method (I),
⇒ 2 × 10 × 15 = ½ × 2 (v² - 20²)
⇒ 300 = v² - 400
⇒ v² = 300 + 400
⇒ v = √700
⇒ v = 10√7 m/s or 26.45 m/s
Thus, the velocity with which the ball hits the ground is 10√7 m/s or 26.45 m/s.
Hope this is helpful!!!!
it's your answer.......
.
....
...
..
.
.
.
.
Thank you..
.
.
.
.
.
.
so much...
