Question

8. A car is travelling at 20 m/s along a road. A child runs out into the road 50 m ahead and the car driver steps on the brake pedal. What must the car’s deceleration be if the car is to stop just before it reaches the child?

Answer 1

heya.......



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 .



tysm......#gozmit