Question

If a body is dropped freely from a height of 20 m, then velocity of the body on reaching to the ground is (g=10 m/sq)

Answer 1

Answer:

20 m/s

Explanation:

v = root 2gh

  = 2X10X20

   = root 400

  = 20 m/s

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Answer 2

Answer:

The velocity of the body on reaching the ground is 20 m/s

Explanation:

Given: A body is dropped freely from a height of 20 m.

To find: The velocity of the body on reaching the ground

Solution:

The force acting on the body immediately after it is dropped is the gravitational force which accelerates the body by acceleration due to gravity.

The velocity and time of the body at any point can be calculated using equation of motion.

Body under free fall,

$v^{2} = 2gh$

$t = \frac{v}{g}$

When a body is dropped from a height, gravitational force allows it to move.

Free fall is the term for motion of a body due to gravity.

The body accelerates with constant acceleration due to gravity.

The velocity of a freely falling body at any position is given by

$v^{2} - u^{2} = 2gh$

where,

h = vertical distance

u = initial velocity

g= acceleration due to gravity i.e 10 $m/s^{2}$

Here  the object is dropped so the initial velocity of the object is zero.

Therefore the equation will be,

$v^{2} = 2gh$

The body  is dropped from height 20 m,

The vertical distance travelled by body on reaching the ground is the height from which it is dropped i.e. 20 m.

Therefore

$v^{2} =$ 2 × 10 × 20

    = $400m^{2} /s^{2}$

The velocity of the body on reaching the ground is 20 m/s

Velocity of a freely falling body is related to the time.

Therefore the equation is

v = u + gt

u = o

v = gt

$t = \frac{v}{g}$

$t = \frac{20}{10}$

t = 2 sec

⇒ v = √400

⇒ v = 20 m/s

Final answer:

The velocity of the body on reaching the ground is 20 m/s

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