3. A lorry accelerates uniformly from \(5 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) to \(20 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) in 30 seconds.
- Find how far it travels while accelerating.
- Find, in seconds correct to 2 decimal places, the length of time it takes for the lorry to cover the first half of this distance.
(6 marks)