To understand this, we have to take it step by step. Firstly, if the speed is doubling, then that means kinetic energy increases by a factor of 4, since:

K.E = 12mv2 therefore K.E v2

So 2v leads to (2)2K.E = 4K.E

Now that kinetic energy has increased by a factor of 4, the car has to do more work to slow down to a stop.

Since W = F x d, therefore W d

So 4W leads to 4d

Therefore, braking distance d increased by a factor of 4 as well!

- Two magnets attracting each other
- An apple falling from a tree
- Charges produced by friction
- None of these