Question

A train is moving with a velocity of 400m/s. What is the retardation if it covers 8km before it stops.​

Answer 1

Answer:

retardation = 10m/s^2 or acceleration = 10m/s^2

Explanation:

v = 400 m/s

u = 0 m/s

s = 8000 m

a = ?

v^2 - u^2 =  2*a*s

160000 - 0 = 2* a *8000

160000 = 16000 * a

a = 160000/16000

a= 10

retardation = -ve acceleration

retardation = 10m/s

aceeleration = -10m/s

Answer 2

Answer:

Explanation:

Solution,

Here, we have

Initial velocity, u = 400 m/s

Final velocity, v = 0 (As train stops)

Distance covered, s = 8 km = 8000 m

To Find,

Retardation, a = ?

According to the 3rd equation of motion,

We know that

v² - u² = 2as

So, putting all the values, we get

v² - u² = 2as

⇒ (0)² - (400)² = 2 × a × 8000

⇒ 160000 = 16000a

⇒ 160000/16000 = a

⇒ a = 10 m/s

Here, Retardation, a = - 10 m/s².

Hence, the retardation of train is - 10 m/s².

Some Important Term,

Retardation - When the final speed of a body is less than its initial speed, the body is said to be retardation. Retardation can also be expressed as acceleration with a minus (-) sign.