Question 20
Density and UpthrustA piece of wood floats inside water at room temperature with a fraction of it above the liquid surface. As the temperature of the water is raised, the part of the wood above the liquid will
- A.decrease because the density of water decreases with temperature
- B.increase because the density of water decreases with temperature
- C.decrease because the density of water increases with temperature
- D.increase because the density of water increases with temperature
Show the answer and explanation
Answer: A (decrease because the density of water decreases with temperature)
Explanation
Above 4 °C water becomes less dense as it warms, so the wood must displace more water to get the same upthrust. It sinks a little deeper, leaving less above the surface.