Question

A moving train is brought to rest within 20 second by applying brakes.Find the initial velocity,if the retardation due to brakes is 2ms-²

Answer 1

Initial velocity = Final velocity + (Acceleration × Time)
Initial velocity = 0 + (2 × 20)
= 0 + 40
= 40 m/s2

Answer 2

Explanation:

GIVEN :-

• Acceleration , a = -2 m/s²

• Final velocity , v = 0 m/s

• Time , t = 20 sec

TO FIND :-

• The initial velocity , u.

SOLUTION :-

★ By using 1st equation of motion ★

→ v = u + at

v = final velocity.

u = initial velocity.

a = acceleration.

t = time taken.

→ 0 = u + (-2) × 20

→ 0 = u - 40

→ u = 40 + 0

→ u = 40

Hence the required initial velocity is 40 m/s.