Scalar and vector quantities

Define a vector quantity

• magnitude only

• both magnitude and direction

• direction only

Define a scalar quantity.

• A quantity with magnitude and direction

• A quantity with direction only

• A quantity with magnitude only

Give three examples of vector quantities.

• Distance, speed and mass

• Displacement, velocity and force

• Distance, speed and force

Give three examples of scalar quantities.

• Distance, speed and force

• Distance, displacement and mass

• Distance, speed and mass

James says “the force of air resistance on the parachute is 50N”. What else should James say in order to be completely correct? Why does he need to add this information?

• “The force is acting upwards” – he should say this because force is a vector quantity and so needs direction as well as magnitude.

• “The force is acting upwards” – he should say this because force is a scalar quantity and so needs direction as well as magnitude.

• “The force is acting upwards” – he should say this because force is a vector quantity and so needs direction only.

Molly says “the mass of the parachutist is 75kg towards the centre of the Earth”. What is wrong with this statement? Why is it wrong?

• The statement should say the magnitude of the mass and give a direction as mass is a scalar quantity.

• The statement should just say the magnitude of the mass and not give a direction as mass is a scalar quantity.

• The statement should just say the magnitude of the mass and not give a direction as mass is a vector quantity.

Look at this diagram. Name the vector quantities shown.

• friction

• air resistance

• Push from slope on sledge P; weight of sledge and boy; resistive forces on sledge and boy.

“Energy” is a scalar quantity. Explain why.

• Energy can only have direction and not magnitude

• Energy can only have magnitude not direction

• Energy can only direction

“Acceleration” is defined as “rate of change of velocity”. Is acceleration a scalar or vector quantity? Explain why.

• A scalar quantity as it is the rate of change of a vector quantity.

• A vector quantity as it is the rate of change of a vector quantity.

“Power” is defined as “rate of transfer of energy”. Is power a scalar or vector quantity? Explain why.

• A scalar quantity as it is the rate of change of a scalar quantity.

• A vector quantity as it is the rate of change of a scalar quantity.