Question

A Locopilot applies the brakes and slows down the
speed of the train from 65m/s. 1o 40 m/s in
5 sec. Calculate the acceleration of the train in S.I. unit.​

Answer 1

Given :

• Initial velocity, u = 65 m/s
• Final velocity, v = 40 m/s
• Time, t = 5 seconds

To find :

• Acceleration, a

According to the question,

➞ v = u + at [ First equation of motion ]

Where,

• v = Final velocity
• u = Initial velocity
• a = Acceleration
• t = Time taken

➞ Substituting the values,

➞ 40 = 65 + a × 5

➞ 40 - 65 = 5a

➞ - 25 = 5a

➞ - 25 ÷ 5 = a

➞ - 5 = a

• So, the acceleration of the train is - 5 m/s². Negative signs means retardation.

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Answer 2

• Given

• Initial velocity = 65 m/s
• Final velocity = 40 m/s
• Time = 5 s

• To find

• Acceleration of the train

• Solution

• To find acceleration of the train we will use the first equation of motion. And substitute the values in it.

• v = u + at

where,

• v = Final velocity
• u = Initial velocity
• a = Acceleration
• t = Time taken

Substituting the given values,

⇒ 40 = 65 + a × 5

⇒ 40 = 65 + 5a

⇒ 40 - 65 = 5a

⇒ - 25 = 5a

⇒ -25/5 = a

⇒ -5 = a

• Accleration of the train = - 5 m/s²

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Velocity -

• It is distance travelled by a body in one second in a particular direction.
• It is a vector quantity.
• Its S.I. unit is m/s.

Acceleration -

• It is the rate of change of velocity of a body.
• It is vector quantity.
• Its S.I. unit is $\sf{m/s^2}$

Equation of motion -

• First equation of motion -
• v = u + at

• Second equation of motion -
• s = ut + $\sf{\dfrac{1}{2} at^2}$

• Third equation of motion -
• $\sf{v^2 - u^2 = 2as}$