Linear Motion

Question 1

scalar quantity

Answer 1

has only a magnitude - no direction in space

Question 2

vector quantity

Answer 2

has both magnitude and direction

Question 3

displacement

Answer 3

• the distance moved in a particular direction
• symbol = s
• unit = m

Question 4

velocity

Answer 4

• the rate of change of displacement with respect to time
• symbol = u or v
• unit = m/s
  (v = s/t)

Question 5

average velocity

Answer 5

• the distance travelled divided by the time taken
• s/t
• u+v/2

Question 6

constant velocity

Answer 6

• the object does not speed up, slow down or change direction
• u = v

Question 7

measuring velocity with a ticker tape

Answer 7

• measure 11 dots (10 spaces)
• times by 0.05 = v in m/s
• or % by 100 × 5 (cm to metres)

Question 8

acceleration

Answer 8

• the rate of change of velocity with respect to time
• symbol = a
• unit = m/s²
• v-u/2

Question 9

derivation of v = u + at

Answer 9

1) use acceleration formula

2) multiply both sides by t

Question 10

derivation of s = ut + 1/2 at²

Answer 10

1) let two equations for average velocity equal each other s/t = u + v/2
2) multiply both sides by t
3) substitute (u + at) for v
4) simplify into 1 line
5) divide equation by 2

Question 11

derivation of v² = u² + 2as

Answer 11

1) start with equation 1 - v = u + at
2) square both sides
3) multiply out brackets
4) take out 2a ; 2a( ut + 1/2 at²)
5 replace ( ut + 1/2 at²) with s