Question

A body is moving with a velocity of 15m/s . if the motion is uniform, what will be the volicty after 10 sec?

(a) 10 m/s. (b) 150 m/s. (c) 15 m/s. (d) 1.5m/s​

Answer 1

Answer:

• The velocity (v) after 10 sec is 15 m/s

Given:

1. Initial velocity (u) = 15 m/s
2. time period (t) = 10 sec.

Explanation:

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This is a case of uniform motion, where velocity is constant. in this case the initial velocity i.e. 15 m/s is constant. and, we know that if velocity is acceleration will be zero, as differentiating a constant term gives zero.

So, clearly as the velocity after 10 sec will also be 15 m/s.

Now, lets prove it mathematically,

From the first kinematic equation we know,

⇒ v = u + at

Here,

• v Denotes final velocity.
• u Denotes initial velocity.
• a Denotes acceleration.
• t Denotes time period.

Substituting the values,

⇒ v = 15 + (0 × 10)    ∵ [a = 0 m/s²]

⇒ v = 15 + 0

⇒ v = 15

⇒ v = 15 m/s

∴ The velocity (v) after 10 sec is 15 m/s.

Hence, Option-C is correct !

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Answer 2

Answer

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The body is moving with uniform velocity means the velocity of body is constant at every second.

$\longrightarrow$As, velocity is not changing and is constant velocity after every second will be equal.

$\longrightarrow$So the velocity of body after 10 sec will also be 15m/s.

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Verification -

By 1st equation of motion -

v = u + at

━━━━━━━━━━━━━━━━━━━━━━━━━━

where -

$\longrightarrow$v is final velocity

u is initial velocity

$\longrightarrow$a is acceleration i.e change of velocity

$\longrightarrow$t is time

━━━━━━━━━━━━━━━━━━━━━━━━━━

$\longrightarrow$u = 15 m/s

$\longrightarrow$a = 0 ( because velocity is constant and hence not changing )

$\longrightarrow$t = 10 sec

━━━━━━━━━━━━━━━━━━━━━━━━━━

$\longrightarrow$v = 15 + (0)(10)

$\longrightarrow$v = 15 + 0

$\longrightarrow$v = 15 m/s

Hence verified.

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Thanks