Practice YOU CAN DRAW ON THE GRAPH FOR THIS QUESTION Here is a speed-time graph for a train (a) Work out an estimate for the distance the train travelled in the first 20 seconds. Use 4 strips of equal width (b) Is your answer to (a) an underestimate or an overestimate of the actual distance the train travelled? Give a reason for your answer. (c) By drawing a suitable tangent, find an estimate of the gradient to the curve at t=15. Give the units of your answer. 25 20 15 Speed (m/s) 10 15 20 25 0 10 Time (5) pint RIA 31 on the