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 .__