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

how will we find time in this question?

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Solution

according to the third equation of motion
v² - u² = 2as
final velocity will be zero as the car has been stopped by the application of the brakes.
(0)² - (20)² = 2 into 50 into a
-400 = 100a
a = -4 m/s²

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

according to the third equation of motion v2 - u2 = 2as final velocity will be zero as the car has been stopped by the application of the brakes. (0)2 - (20)2 = 2 into 50 into a -400 = 100a a = -4 m/s2

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

how will we find time in this question?

according to the third equation of motion
v² - u² = 2as
final velocity will be zero as the car has been stopped by the application of the brakes.
(0)² - (20)² = 2 into 50 into a
-400 = 100a
a = -4 m/s²