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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 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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Initial velocity, u = 20 m/s

Final velocity, v = 0 m/s

Distance, s = 50 m

Using relation, v2 = u2 + 2as

02 = (20)2 + 2 x a x 50

02 = 400 + 100a

a = \(\frac{-400}{100}\) = -4 m/s

The car’s deceleration must be 4 m/s2.

This post was modified 2 years ago by Mayank1444
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