Question

which of the following is a vector quantity 1.mass of proton 2.energy of thermal neutron 3.velocity 4.volume

Answer 1

velocity is a vector quantity

Answer 2

Velocity (3) is a vector quantity.

Explanation:

• Scalar quantities are those that have magnitude only . For example weight is a scalar quantity because it has magnitude only like if someone weighs 60 kg , he is 60 kg only . It is not directional like 60 kg to the east . Hence, only magnitude.
• Whereas vector quantities are those that have magnitude as well as direction. For example Force is a vector entity because when someone says he applied a force on a box , the magnitude of which lets say 5N . Therefore, we say 5N of force has been applied on the box from the west to move the box to the right .
• From the examples,

1. Mass = scalar quantity as it has only magnitude.
2. Energy = It is a scalar quantity because energy is the capacity to do work and work itself is a scalar quantity.
3. Velocity = Velocity is a vector quantity as velocity is displacement upon time and displacement is a vector quantity and as we know, displacement can be 0 also. Therefore, direction is a very important aspect to be specified while calculating velocity.
4. Volume = Volume is a scalar quantity as it is measurable only . Volume is directly proportional to cube of side of any object and as side is a scalar quantity. Hence, volume is also scalar.