Question

Pls help, I will follow you and mark brainliest if I am satisfied pls solve with complete steps and step by step ​

Answer 1

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✤ Required Answer:

✒ GiveN:

• Initial velocity = 20 m/s
• Retardation = 4 m/s²
• Distance covered = 42 m

✒ To FinD:

• Final velocity of the body.....?
• Time taken of the body....?

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✤ How to Solve?

This question can be solved using the three equations of motion which is used when body undergoes uniform acceleration or retardation. These equations are:

• v = u + at
• s = ut + 1/2 at²
• v² = u² + 2as

Here, v = final velocity, u = initial velocity, s = distance covered, t = time taken, a = acceleration

♠️ So, By using these equations, let's solve the above question....

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✤ Solution:

We have,

• s = 42 m
• u = 20 m/s
• a = -4 m/s²

By using 3rd equation of motion,

➝ v² = u² + 2as

➝ v² = 20² + 2 × (-4) × 42

➝ v² = 400 + (-336)

➝ v² = 64

➝ v = 8 m

[Neglecting v = -8 m/s]

✒ Therefore, Final velocity of the body = 8m/s

Now, finding the time taken.

Now we also have,

• v = 8 m/s

So, For easier calculation we will use 1st equation of motion$.$

By using 1st equation of motion,

➝ v = u + at

➝ 8 = 20 + (-4)t

➝ 4t = 20 - 8

➝ 4t = 12

➝ t = 3s

✒ Time taken by the body = 3s

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Answer 2

Answer:

Explanation:

Question,

A body moving with a velocity of 20 m/s undergoes a retardation of 4 m/s until it covers a distance of 42 m. Find a. Final velocity b. Time taken.

Solution,

Here, we have

Initial velocity, u = 20 m/s

Retardation, a = - 4 m/s²

Distance covered, d = 42 m.

To Find,

a. Final velocity, v = ?

b. Time taken, t = ?

According to the 3rd equation of motion,

We know that

v² - u² = 2as

So, putting all the values, we get

v² - u² = 2as

⇒ v² - (20)² = 2 × (- 4) × 42

⇒ v² - 400 = - 336

⇒ v² = - 336 + 400

⇒ v² = 64

⇒ v = - 8, 8. (As speed can't be negative)

⇒ v = 8 m/s.

Hence, the final velocity of the body is 8 m/s.

Now, we will find time taken,

According to the 1st equation of motion,

We know that,

v = u + at

So, putting all the values, we get

v = u + at

⇒ 8 = 20 + (- 4) × t

⇒ 8 - 20 = - 4t

⇒ - 12 = - 4t

⇒ 12/4 = t

⇒ t = 3 seconds.

Hence, the time taken by the particle is 3 seconds.