Read each statement below carefully and state, with reasons and examples, if it is true or false:
A scalar quantity is one that
A. is conserved in a process
B. can never take negative values
C. must be dimensionless
D. does not vary from one point to another in space
E. has the same value for observers with different orientations of axes.
A. False
A scalar quantity is one which only has magnitude and no direction for e.g. Speed, Pressure, Energy, Temperature etc. they need not always be conserved in a pressure for e.g. In most thermodynamic process pressure, Temperature of the system varies, in inelastic collisions Energy of particles are not conserved etc. so we cannot say scalar quantity is always conserved in a process
B. False
Scalar quantities do not have a direction but they can take both positive and negative values and the sign does not depict direction for eg. Temperature is a scalar quantity and can have negative values but its negative sign does not depict direction because it does not have a direction it’s just a value less than reference 0 value
C. False
Scalar quantities, just like vector quantities have units hence dimensions as they have magnitude which is measured with appropriate unit and hence have a dimension for e.g. Distance is a scalar quantity and is measured in metres or its unit is metre(m) so its dimension is L ,Speed is a scalar quantity and its unit is m/s so its dimension is LT-1 likewise scalar quantities have dimensions.
D. False
Scalar quantities can vary from point to point in space and values need not be constant in space just like vector quantities for eg. Potential energy is a scalar quantity, and potential energy is body possessed by the body due to virtue of its position and as the position changes the potential energy certainly changes like gravitational potential energy of an object depends on the height from ground i.e. the quantity vary with change in position and hence vary from one point to another in space
E. True
Scalar quantity does not have a direction, it only has magnitude and if orientation of axes is changed only direction of observation changes and magnitude remain same but since scalar quantity does not have a direction, direction of observation is meaningless and as magnitude is constant to there is no change at all.