Scalars and vectors

Question 1

How can vector quantities show their direction?

Answer 1

With + and -.

(A force of +4 N may be balanced by a force of -4 N. A distance walked to the right of 20 m is a displacement of +20 m, the same distance to the left from the same starting point is a displacement of -20 N.)

Question 2

What is a scalar quantity?

Answer 2

Quantities with a size or magnitude but no specific direction.

Question 3

What is a vector quantity?

Answer 3

A quantity with size or magnitude and a specific direction.

Question 4

Name three scalar quantities.

Answer 4

• mass
• speed
• distance
• energy
• temperature

Question 5

Name three vector quantities.

Answer 5

• force/weight
• velocity
• displacement
• acceleration
• momentum

Question 6

Which of these quantities is a vector?

A: temperature
B: energy
C: speed
D: electric field

Answer 6

D: electric field

Question 7

Explain why a satellite can be said to be moving at a constant speed but not at a constant velocity.

Answer 7

The satellite travels at a constant speed as it covers an equal distance per second

but it’s direction is constantly changing as it moves in a circle

so it’s velocity must be changing as velocity is a vector quantity with both size and direction.

Question 8

Describe the difference between a scalar and a vector.

Answer 8

A scalar has a size, whereas a vector has a size and a specific direction.

Question 9

Describe an example which shows the difference between a scalar and a vector.

Answer 9

Speed is a scalar quantity and may have a value of 5 m/s. Velocity may also have a value of 5 m/s but a direction of north.

Question 10

Which of these quantities is a scalar?

A: velocity
B: acceleration
C: mass
D: weight

Answer 10

C: mass

Question 11

A boy has a speed of 4 m/s when running. State his (a) speed and (b) velocity when he is running in the opposite direction.

Answer 11

a) 4 m/s

b) -4 m/s