Question

A car was running with the velocity of 20m/s. what will be its velocity after 30s if its acceleration is 5m/s^2

Answer 1

Explanation:

Correct option is

B

8 s

Given Final velocity (v) = 50 m/s

Initial velocity (u) = 30 m/s

Acceleration (a) = 2.5 m/s

2

We know v = u + at

∴ 50 = 30 + 2.5 t

⇒ 50 - 30 = 2.5 t

⇒

2.5

20

= t or 8 = t

∴ Time taken to accelerate = 8 seconds

Answer 2

Understanding the concept: This question says that we have to find out the final velocity of the car whose initial velocity is 20 mps and it is moving with an acceleration of 5 mps sq. in 30 seconds.

Provided that:

• Initial velocity = 20 mps
• Acceleration = 5 mps sq.
• Time = 30 seconds

To calculate:

• Final velocity

Solution:

• Final velocity = 170 mps

Using concept(s):

• We can use either first equation of motion or acceleration formula to solve this question.

Using formula(s):

• First equation of motion:

• v = u + at

• Acceleration formula:

• a = (v-u)/t

Where, v denotes final velocity, u denotes initial velocity, t denotes time taken and a denotes acceleration.

Required solution:

~ By using acceleration formula!

→ a = (v-u)/t

→ 5 = (v-20)/30

→ 5 × 30 = v - 20

→ 150 = v - 20

→ 150 + 20 = v

→ 170 = v

→ v = 170 mps

→ Final velocity = 170 mps

~ By using first equation of motion!

→ v = u + at

→ v = 20 + 5(30)

→ v = 20 + 150

→ v = 170 mps

→ Final velocity = 170 mps $\:$