Answer the following:
(1) A glass of water has an ice cube floating in water. The water level just touches the rim of the glass. Will the water overflow when the ice melts? Give reasons.
(2) A block of plastic is released under water. Will it sink or come up to the surface of water? Give reasons.
Answer the following:
(1) A glass of water has an ice cube floating in water. The water level just touches the rim of the glass. Will the water overflow when the ice melts? Give reasons.
(2) A block of plastic is released under water. Will it sink or come up to the surface of water? Give reasons.
(1) As we know, the density of ice is less than that of water, so it floats on a water surface. When the ice melts, its volume decreases because density of water is more (mass of ice remains same).
That means, mass of ice = mass of water that has melted from ice.
Due to this reason, the water will not overflow when the ice melts.
(2) A block of plastic released under water will come up to the surface of water.
Two forces act on an object immersed in water. One is the gravitational force, which pulls the object downwards, and the other is the buoyant force, which pushes the object upwards. If the upward buoyant force is greater than the downward gravitational force, then the object comes up to the surface of the water as soon as it is released within water. Due to this reason, a block of plastic released under water comes up to the surface of the water.
(1) As we know, the density of ice is less than that of water, so it floats on a water surface. When the ice melts, its volume decreases because density of water is more (mass of ice remains same).
That means, mass of ice = mass of water that has melted from ice.
Due to this reason, the water will not overflow when the ice melts.
(2) A block of plastic released under water will come up to the surface of water.
Two forces act on an object immersed in water. One is the gravitational force, which pulls the object downwards, and the other is the buoyant force, which pushes the object upwards. If the upward buoyant force is greater than the downward gravitational force, then the object comes up to the surface of the water as soon as it is released within water. Due to this reason, a block of plastic released under water comes up to the surface of the water.
