Question

Find the initial velocity of a car which is stopped in 10seconds by applying brakes . The

retardation due to brakes is 2.5 ms-2

.​

Answer 1

Answer:

25 m/s

Explanation:

Given:

• Time taken = t = 10 seconds
• Acceleration = a = -2.5 m/s²
• Final velocity = v = 0 m/s

To find:

• Initial velocity = u

Using the first equation of motion:

V=u+at

0=u+ -2.5×10

0=u -25

u=0+25

u=25 m/s

The initial velocity of the car is equal to 25 m/s

More:

• Second equation of motion = s=ut+1/2 at²
• Third equation of motion = v²-u²=2as
• Distance travelled in nth second equation of motion = sn = u+a/2(2n-1)
• Average speed = total distance/total time
• Average velocity = total displacement / total time

Answer 2

$\huge\mathcal{\underbrace{SOLUTION:-}}$

GIVEN :-

• A car is stopped in 10 seconds by applying brakes .

• The retardation due to brakes is 2.5m/s² .

TO FIND :-

• The initial velocity of the car .

CALCULATION :-

✍️ Here,

• time (t) = 10 second

• acceleration (a) = - 2.5 m/s²

[Here, acceleration is the retardation. So, it is taken as negative.]

✍️ Brakes are applied on the car, so after sometime the car is stopped .

• Hence, final velocity (v) = 0 m/s

✍️ Now, we use the Equation of Motion .

$\checkmark\:\mathcal{\green{v\:=\:u\:+\:at\:}}$

• v = final velocity .

• u = initial velocity .

• a = acceleration .

• t = time .

$\rm{\implies\:0\:=\:u\:+\:(-2.5)\times{10}\:}$

$\rm{\purple{\implies\:u\:=\:25\:m/s\:}}$

$\therefore\:\rm{\red{The\:initial\:velocity\:of\:car\:is\:\:25\:m/s\:.}}$