Question

Whatever floats your boat You and your two friends Tom Sawyer and Huck Finn each weigh...

Whatever floats your boat

You and your two friends Tom Sawyer and Huck Finn each weigh 70 kg and want to build a raft out of

logs to float from Hope to Vancouver on the Fraser River. The Birch logs that you have found are 3.0 m

long, 0.5 m diameter and have a specific density of 0.70. You want to know how many logs you need to

use to build your raft so that you all keep your feet dry.

Homework Answers

Answer #1

Total weight of the logs + weight of 3 persons = Buoyant force
n x L x VL x g + 3 x m x g = n x W x VL x g          ...(1)
Where n is the number of logs, L is the density of logs, VL is the volume of logs, m is the mass of each person, W is the density of water and g is the acceleration due to gravity.

n x L x VL + 3 x m = n x W x VL         [Cancelling g from (1)]
n VL x [W - L] = 3m
n = 3m / [VL x [W - L]]                    ..(2)
VL = 3 x x (0.25)2
= 0.589 m3
Substituting in (2),
n = (3 x 70) / [0.589 x [1 x 103 - 0.7 x 103]
= 210/176
= 1.2
At least 2 logs are needed.

Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT