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Standard IX

Physics

Derivation of Position-Velocity Relation by Graphical Method

A car is trav...

Question

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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Similar questions

Q. 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?

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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