A firefighter stands on a skateboard and holds in his hands a hose connected to a water tank. He doesn’t move at first but after opening the valve on the pipe, the water starts to flow out at a constant rate of 
. The mass flow rate of the water is 
.
How far does the firefighter move in 6 seconds if the total mass of the skateboard and firefighter is 80 kg? Friction is ignored.
What is the distance travelled if a valve is connected to the pipe to reduce the cross-section of the jet in a ratio of 3 : 2?
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