Question 12
Derrick is travelling in a train at 21 metres per second. A 9-metre-long truck travelling in the opposite direction passes Derrick in $\frac38$ second. What is the truck’s speed in metres per second?
Assume constant speeds during the pass; Derrick is treated as a point. The interval runs from the front of the truck reaching him until its back passes him.
Assume constant speeds during the pass; Derrick is treated as a point. The interval runs from the front of the truck reaching him until its back passes him.