Question

Q4.Find the initial velocity of a car which is stopped in 10 seconds by applying brakes. The retardation due to brakes is 2.5m/s.​

Answer 1

Answer:

Answer

Initial velocity, u=?

Final velocity, v=0m/s (car is stopped)

Acceleration, a=−2.5m/s

2

(negative because it is retardation)

Time, t=10s

Use the relation of the first equation of motion:

v=u+at

0=u+(−2.5)×10

u=25m/s

Answer 2

Question :

Find the initial velocity of a car which is stopped in 10 seconds by applying brakes. The retardation due to brakes is 2.5m/s.

Answer :

• final velocity is 0 m/s

• acceleration is 2.5 m/s²

• time is 10 seconds

• initial velocity = ?

$\bf\purple{Formula\:to\:be\:used:}$

$\bf\green{v = u + at }$

• v is final velocity that is 0

• u is initial velocity that we have to find

• a is acceleration that is 2.5

• t is time that is 10

$\longrightarrow\bf{ 0 = u + 2.5\times 10}$

$\longrightarrow\bf{ 0 = u + 25}$

$\longrightarrow\bf{ 0 - u = 25 }$

$\longrightarrow\bf{ - u = 25 }$

Therefore initial velocity is 25 m/s