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Question
Find the average force needed to accelerate a car weighing 500 kg from rest to 72 km/h through a distance of 25 m.
Solution
\[\text{ Given } : \]
\[\text{ Mass of the car, m = 500 kg }\]
\[\text{ Initial velocity of the car, u = 0 }\]
\[\text{ Final velocity of the car, } \nu = 72 \text{ km/h = 20 m/s }\]
\[a = \frac{\left( \nu^2 - u^2 \right)}{2s}\]
\[a = \frac{400}{50} = 8 \text{ m/ s}^2\]
Force needed to accelerate the car,
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