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Why does a small puddle of water evaporate at room temperature, even though the temperature is way below the boiling point of water?

To understand why the water evaporates, we need to know what we mean when we say something has a certain temperature. Temperature is proportional to the average kinetic energy of the microscopic molecules in...
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Answered by Ellen S. • Physics tutor
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According to Newton's third law, every action has an equal and opposite reaction. Why then does a box move when I push it? Shouldn't the two opposing forces cancel out to a zero net force?

The key to this question is realising that the action and corresponding reaction refer to forces that act on different objects . When I push the box, I exert a force on the box. As a result of this force, th...
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Answered by Ellen S. • Physics tutor
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Define the term osmosis

Osmosis is the movement of water particles from an area of high concentration to an area of low concentration through a partially permeable membrane along a concentration gradient.
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Answered by Alice D. • Biology tutor
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State the function of the enzyme lactase

Break down the disaccharide lactose to the monosaccharides glucose and galactose.
Answered by • Biology tutor
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A ball with radius 10cm is filled with an ideal gas at pressure 2*(10)^5Pa and temperature 300K. The volume of the gas is changed at constant pressure so that the radius of the ball is reduced with 1cm. Find the amount of gas and the new temperature

In a question like this, you will be given that the molar gas constant is R = 8.31JK -1 mol -1 . However, committing this to memory will be helpful. We should use the ideal gas law: PV = nRT but the volume o...
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Answered by Ivan G. • Physics tutor
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