Why does the jar of a kitchen mixer become hot after running for a few minutes?
AThe electric current passes through the jar
BThe motor releases steam
CFriction between moving parts (and between blades and food) produces heat
DSunlight is concentrated by the lid
Answer & Solution
Correct answer: C. Friction between moving parts (and between blades and food) produces heat
When a mixer runs, its blades move rapidly against food and the moving mechanical parts rub against each other. Friction at all these contacts converts mechanical energy into heat. The same principle is why rubbing palms warms them up and why striking a matchstick lights a fire.
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