Question

A car travelling at 90 m/s comes to rest in 10 sec , calculate its distance travelled after brakes were applied.​

Answer 1

Please refer the above attachment I hope it helps .

Answer 2

Given data:-

• A car travelling at 90 m/s comes to rest in 10 sec.
• at the end brakes were applied.

Here,

—› Initial velocity ( u ) = 90 m/s

—› Final velocity ( v ) = 0

—› Time taken by car ( t ) = 10 sec

—› Displacement of car ( s ) = ?

Solution:-

To find acceleration

—› a = [v - u]/t

—› a = [0 - 90]/10

—› a = - 90/10

—› a = - 9 m/s²

Here, we use scalar form for motion in one dimension (linear motion).

—› v² = u² + 2as

—› v² - u² = 2as

—› ( 0 )² - ( 90 )² = 2 × ( - 9 ) × s

—› - 8100 = - 18 × s

{ minus ( - ) sign cancel from both side }

—› 8100 = 18 × s i.e.

—› s = 8100/18

—› s = 450 m

Hence, 450 m distance travelled by car before breaks applied.