Hint
Choose and retain a positive direction; distinguish signed quantities from magnitudes. Use the slope or position change of the stated straight segment, with its own duration.
Worked solution
(a)
Use the slope or position change of the stated straight segment, with its own duration.
The rising slope is \(7\) m/s.
Answer: \(7\) m/s
(b)
Use the slope or position change of the stated straight segment, with its own duration.
Its displacement change is −14 m over 4 s, giving \(\displaystyle - \frac{7}{2}\) m/s.
Answer: \(\displaystyle - \frac{7}{2}\) m/s
(c)
Identify the horizontal position segment and subtract its endpoint times.
The middle segment is horizontal for 1 s.
Answer: \(1\) s
Maths4U indicative marking guidance
Maths4U indicative marking guidance, not an official mark scheme. Credit complete valid alternative methods and consequential reasoning. An unexplained result does not earn a method mark.
(a) · 2 marks
- 1 mark: Use the slope or position change of the stated straight segment, with its own duration.
- 1 mark: Give the correct requested result, retaining signs, units and any domain restrictions.
Alternative methods: Any complete mathematically valid alternative method with the same restrictions and equivalent exact result is acceptable.
Common error: Do not treat the height of a displacement graph as a speed.
(b) · 2 marks
- 1 mark: Use the slope or position change of the stated straight segment, with its own duration.
- 1 mark: Give the correct requested result, retaining signs, units and any domain restrictions.
Alternative methods: Any complete mathematically valid alternative method with the same restrictions and equivalent exact result is acceptable.
Common error: A falling segment adds positive distance even though its displacement is negative.
(c) · 2 marks
- 1 mark: Identify the horizontal position segment and subtract its endpoint times.
- 1 mark: Give the correct requested result, retaining signs, units and any domain restrictions.
Alternative methods: Any complete mathematically valid alternative method with the same restrictions and equivalent exact result is acceptable.
Common error: Do not treat the height of a displacement graph as a speed.
Total: 6 marks.