You have constructed a raft that is 2 m long,2 m wide,0.100 m thick.if the mass of the raft is 50 kg and your mass is 55 kg,how many 55 kg friends can cross a river with you during one trip?

volume = 2 * 2 * 0.1 = 0.4 m^3

density of fresh water is about 1000 kg/m^3
so it displaces 0.4 * 1000 = 400 kg of water
thus including its own mass it can carry 400 kg
so
400 = 50 + 55 + 55 n
55 n = 295
n = 5.36 friends
If you want to keep the friends I recommend taking 5 and not carving a 6 th up and discarding 0.64 friend.

Did you know?

Did you know that the buoyancy of an object floating in water is determined by its volume? In this case, the raft has a volume of 2 m x 2 m x 0.100 m = 0.400 cubic meters. The total mass of the raft and the person is 50 kg + 55 kg = 105 kg. To determine how many 55 kg friends can join the trip, we need to compare the total mass to the volume of the raft. The density of water is approximately 1000 kg/m^3. Therefore, the weight of the water displaced by the raft is 0.400 m^3 x 1000 kg/m^3 = 400 kg. Since the total mass on the raft is 105 kg, this means that 400 kg - 105 kg = 295 kg of water can still be displaced. Since each friend weighs 55 kg, we can divide 295 kg by 55 kg to find that approximately 5.36 friends can join the trip. However, since we cannot have a fraction of a person, only a maximum of 5 friends weighing 55 kg each can safely cross the river during one trip on the raft.