Question

A moving train is brought at rest within 20 sec by applying breaks. Find the innicial velocity if the redartation due to break is 2m/sec square

Answer 1

Answer:

40 m/s

Explanation:

Given:

Time taken = 20 seconds (t)

Acceleration = -2 m/s^2 (a)

Final velocity = 0m/s (the train comes to rest finally) (v)

To find:

Initial velocity (u)

We can find the Value of intial velocity by using the first equation of motion which says:

V=u+at

Substituting the values we get,

0 = u + (-2)×20

0 = u-2×20

0 = u-40

u = 0+40

u = 40 m/s

The intial velocity of the moving train is 40 m/s

Answer 2

Explanation:

Given -

v = 0 m/s (final velocity)

t = 20 seconds (time)

a = -2 m/s² (retardation)

To Find -

Initial velocity (u)

As we know that :-

• v = u + at

here,

v = final velocity

u = initial velocity

a = acceleration

t = time

» 0 = u + (-2)×20

» 0 = u - 40

• » u = 40 m/s

Hence,

The initial velocity (u) is 40 m/s

Formula Used -

v = u + at

Some related formulas -

s = ut + ½at²

v² = u² + 2as

here,

v = final velocity

u = initial velocity

a = acceleration

t = time

s = distance travelled