Question

A truck travelling at 54 km/h is slow down to 36 km/h in 10 sec. Find the retardation​

Answer 1

Answer:

Initial velocity (u) = 54 km/hr

Final velocity (v) = (54 - 36) km/hr

Time (t) = 10 seconds

We know v = u - at

⇒ 18 = 54 - a × 10

or 10a = 54 - 18

or a = 36/10

=3.6

∴Retardation = 3.6 km/h

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Answer 2

ANSWER:

Given:

• Initial Velocity = 54km/hr
• Final Velocity = 36km/hr
• Time taken = 10sec

To Find:

• Retardation

Solution:

We are given that,

⇒ Initial velocity (u) = 54km/hr

And,

⇒ Final velocity (v) = 36km/hr

We know that,

To convert km/hr into m/sec, we need to multiply by 5/18.

So,

⇒ Initial velocity (u) = 54 × 5/18 = 3 × 5 = 15m/sec

And,

⇒ Final velocity (v) = 36 × 5/18 = 2 × 5 = 10m/sec

We are also given that

⇒ Time taken (t) = 10sec

By 1st Equation of Motion,

⇒ v = u + at

Substituting the values of v, u and t.

⇒ v = u + at

⇒ 10 = 15 + a(10)

⇒ 10 - 15 = 10a

⇒ -5 = 10a

So,

⇒ a = -5/10

⇒ a = -0.5 m/sec^2

Therefore, the retardation is 0.5m/sec^2