The braking distance of a car, in metres, is directly proportional to the square of its speed in km/h, and can be represented by the equation
`text{braking distance}\ = k xx text{(speed)}^2`
where `k` is the constant of variation.
The braking distance for a car travelling at 50 km/h is 20 m.
- Find the value of `k`. (2 marks)
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- What is the braking distance when the speed of the car is 90 km/h? (1 mark)
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