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Question
A person driving a car suddenly applies the brakes on seeing a child on the road ahead. If he is not wearing seat belt, he falls forward and hits his head against the steering wheel. Why?
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Solution
When the car is moving with some velocity, then the person is also moving with the same velocity. After applying the brakes, the car stops suddenly. The lower part of the driver stops along with the car but the upper part of the person continues to move with the existing velocity. This results in the person hitting his head against the steering wheel due to the inertia of motion.
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