Question

a car is travelling at 20 metre per sec . a child runs out into road 50 metre ahead and the car driver syeps on brake . what must be the car's decelaration br if the car stops just before it reaches the child ?

Answer 1

GIVEN ;-

⇒ Speed of the car = 20 m / s

⇒ Distance of the child from the car when it goes into the road = 50m


TO FIND ;-

⇒ What must the car’s deceleration be if the car is to stop just before it reaches the child?


SOL ;-

⇒ Distance of the child from the car in the road ( S ) = 50 m

⇒ Initial velocity of the car ( u ) = 20 m / s

⇒Final velocity of the car ( v ) = 0 m / s



Now let us find the acceleration using the formula -


2 a s = v² - u ²

Here we need to find the acceleration so let us rearrange the formula ,


we get as - a = u² - v² / 2 as




⇒ a = v² - u² / 2 s

⇒ a = 0 - 20² / 2 × 50

⇒ a = - 400 / 100

⇒ a = - 4 m /s

So acceleration is - 4 m / s

this is your answer..