Question

3. Take the uniform acceleration near the surface of earth to be 9.8 m/
s2
for a free fall. What is the velocity of a body at the end of two second of
free fall, if the initial velocity is zero.
O 9.8 m/s
2 x 9.8 m/s
3 x 9.8 m/s
O 4 x 9.8 m/s
Clear se

Answer 1

Answer:-

Given:

acceleration (g) = 9.8 m/s²

Initial Velocity (u) = 0 m/s

Time (t) = 2 s

We have to find the final velocity.

using first equation of motion,

i.e.,

v = u + at

⟶ v = u + gt

[ In this case a = g and v is the final velocity ]

⟶ v = 0 + (9.8) × (2)

⟶ v = (9.8) × 2 m/s

∴ The velocity of the body after 2 seconds is 2 × 9.8 m/s = 19.6 m/s.

Additional Information :

Three equations of motion are :

• v = u + at

• S = ut + 1/2 at²

• v² - u² = 2aS

Answer 2

Answer:

$\: \: \boxed{\boxed{\rm{\mapsto \: \: \: Firstly \: let's \: understand \: the \: concept \: used}}}$

Here the concept of Equations of Motions have been used. According to this, if we know the equations of motion, then we can easily find out Displacement (s), Final Velocity (v), Time (t), Acceleration (a) and Initial Velocity (u).

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★ Formula Used :-

$\: \: \huge\boxed{\boxed{\boxed{\rm{v \: - \: u \: = \: a \: \times \: t}}}}$

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★ Question :-

Take the uniform acceleration near the surface of earth to be 9.8 m/s²

for a free fall. What is the velocity of a body at the end of two second of

free fall, if the initial velocity is zero.

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★ Solution :-

Given,

» Initial Velocity of the body = u = 0 m/sec

» Acceleration of the body = a = 9.8 m/sec²

» Time taken by the body = t = 2 seconds

Let's apply these values in the formula and find the answer.

⌬ v - u = a × t

⌬ v - 0 = 2 × 9.8

$\: \: \huge{\rm{v \: = \: 2 \: \times \: 9.8}}$

On further calculation,

⌬ v = 2 sec × 9.8 m/sec²

⌬ Final Velocity, v = 19.6 m/sec

$\: \: \boxed{\boxed{\bf{\mapsto \: \: \: Hence, \: the \: final \: velocity \: of \: the \: body \: after \: 2 \: seconds \: of \: free \: fall \: is \: \underline{\underline{19.6 \: msec^{-1}}}}}}$

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$\: \: \huge{\underline{\tt{\mapsto \: \: Let's \: know \: more \: :-}}}$

• First Law of motion : v - u = at

• Second Law of motion : s = ut + ½(at²)

• Third Law of motion : v² - u² = 2as

• Newton's First Law of Motion : It states that every body continues in its state of rest or of uniform motion along a straight line, unless an external force is applied to change that state. This law defines force.

• Newton's Second Law of Motion : It states that the rate of change of momentum of a body is directly proportional to the applied force and the change in momentum takes place in the direction of force applied. This law gives a measure of the force.

• Newton's Third Law of Motion : It states that to every action, there is an equal and opposite reaction.