What is true about kinetic energy?
Responses-
a- Molecules within a substance have kinetic energy when that substance moves.
b- Cold molecules have potential energy but no kinetic energy, as kinetic energy is experienced as heat.
c- Molecules of liquids and gases are in constant motion, so they have kinetic energy.
d- All molecules are in constant motion, so they all have some kinetic energy.
c- Molecules of liquids and gases are in constant motion, so they have kinetic energy.
The correct answer is c- Molecules of liquids and gases are in constant motion, so they have kinetic energy.
The correct option among the given responses is c- Molecules of liquids and gases are in constant motion, so they have kinetic energy.
Explanation:
Kinetic energy is the energy possessed by an object due to its motion. In the context of molecules, kinetic energy refers to the energy of the individual particles that make up a substance.
Option a is incorrect because molecules within a substance can have kinetic energy even when the substance as a whole is not moving. For example, in a gas, the individual gas particles are constantly moving and have kinetic energy, even if the gas itself is not flowing or being transported.
Option b is incorrect because cold molecules can still possess kinetic energy. Kinetic energy is not exclusively experienced as heat but rather as the energy of motion. While temperature is a measure of the average kinetic energy of the molecules, individual molecules can vary in their kinetic energy depending on their velocity.
Option c is correct because molecules in liquids and gases are in constant random motion. The particles move in a variety of directions and at different speeds. This motion constitutes kinetic energy, which is the energy of the particles due to their motion.
Option d is incorrect because not all molecules have kinetic energy. For example, in a solid, the molecules are vibrating in fixed positions and do not possess the translational kinetic energy associated with motion. However, even in a solid, the individual molecules can still have vibrational kinetic energy.