Question

Physics Question:- Find the initiadjdl velocity of a train which is stoppded in 20 seconds by applying brakes. the retardation due to brakes is 1.5m/s²

Answer 1

The above Question falls from "Motion"

Correct Question

_____________________

Find the initial velocity of a train which is stopped in 20 seconds by applying brakes. The retardation due to brakes is 1.5m/s².

_____________________

Given

• Final Velocity (v) = 0 m/s
• Time = 20 s
• Acceleration = -1.5 m/s²

To Find

• Initial Velocity (u)

Formula Used

• v = u + at

Substituting the Values

➭ 0 = u + -1.5 × 20

➭ 0 = u + (-30)

➭ 0 = u -30

➭ u = 30

Therefore, u = 30 m/s

Hence, Initial Velocity (u) = 30 m/s

Additional Information

• Rate of Change of distance is said to be Speed
• The Speed from which the body starts moving is said to be Initial Speed of a body & it is denoted by u
• The Speed which the body acquires after it starts, is said to be Final Speed & is denoted by v
• Rate of Change of Velocity is known as Acceleration

Three Equations of Motion

1. v = u + at
2. s = ut + ½at ²
3. v² - u² = 2as

Answer 2

Given :

• Time taken (t) = 20s
• Final velocity (v) = 0
• Acceleration (a) = -1.5m/s²

To find :

• Initial velocity (u)

Solution :

According to the first equation of motion

→ v = u + at

→ 0 = u + (-1.5) × 20

→ 0 = u - 30

→ u = 30m/s

Hence,

• Initial velocity of train is 30m/s

Additional Information

• s = ut + ½ at² {second equation of motion}
• v² = u² + 2as {third equation of motion}
• The rate of change in velocity is known as acceleration
• S.I unit of acceleration is meter per second square (m/s²)
• SI unit of time is second (s)
• SI unit of speed is meter per second (m/s)