Question

An object of mass 4 kg is dropped from a height of 29m. find it's kinatic energy ,when it is half way down​

Answer 1

Given :

• Mass of body = 4 kg
• Height = 29 m
• Initial velocity = 0 m/s
• gravity ( g ) = 10 m/s²

To Find :

• Kinetic energy of the body when it covered half distance

Solution :

v² - u² = 2as

Here a = g

➨ v² - 0² = 2 * 10 * 14.5

➨ v² = 290 m/s

Kinetic energy = 1/2 mv²

➨ 1/2 ( 4 * 290 )

➨ 1/2 ( 1160 )

➨ 580 J

Kinetic energy of the body is 580 Joules

Answer 2

Given:

Mass of object, m = 4 kg

Height from the object is dropped, H = 29 m

Acceleration due to gravity, g = 10 m/s²

Initial velocity, u = 0

To find:

Kinetic Energy of the object = K.E.

Answer:

Kinetic Energy = 580 J

Solution:

We know,

$\boxed{Kinetic \: Energy = \dfrac{1}{2} \times m \times v^{2}}$

where,

m = mass

v = velocity of the object

Now, to find the final velocity:

v² = u² + 2gh

Height when it is half way down, h = 29/2 = 14.5 m

v² = 0 + 2 × 10 × 14.5

v² = 20 × 14.5

v² = 290 m/s

Using this value,

$\implies\dfrac{1}{2} \times 4 \times 290 \\ \\ \implies2 \times 290 =580$

Therefore, the kinetic energy of the object is 580 J.