Graph gradients and areas
3 exam-style questions. Answers and the mark for each step are on the last page.
- Question 1
(a) A vehicle has speeds 1, 5, 8 and 6 m/s at times 0, 2, 4 and 6 seconds respectively. Use three trapezia, each 2 seconds wide, to estimate the distance travelled from 0 to 6 seconds.
- Question 2
A tangent to a distance-time curve at t = 4 passes through and . Time is in seconds and distance in metres.
(a) Estimate the instantaneous speed at t = 4.
(b) At t = 4 the distance is 18 m. Find the average speed over the first 4 seconds if the distance at t = 0 was 2 m.
- Question 3
A car starts from rest and accelerates steadily to 15 m/s in seconds. It then travels at 15 m/s for 40 seconds, and then slows steadily to rest in 10 seconds. The total distance travelled is 750 m.
(a) Find the value of .
Answers and marks
Question 1
(a) m
- P1 Establishing or an equivalent valid method.
- P1 Establishing or an equivalent valid method.
- A1 Correct answer: m
Question 2
(a) m/s
- M1 Use the gradient of the tangent, not a line from the origin.
- A1 Correct answer: m/s
(b) m/s
- M1 Average speed uses the change in distance over the whole interval.
- A1 Correct answer: m/s
Question 3
(a)
- P1 Recognising that distance is the area under the velocity-time graph.
- P1 Finding the area of the constant-speed and slowing sections: 600 and 75.
- P1 Forming .
- A1 The correct answer, .