Calculate Centre of Mass with Unknown Mass: Ricardo & Carmelita on Canoe

AI Thread Summary
To calculate the center of mass (COM) of the canoe with Ricardo and Carmelita, the initial COM can be expressed as (80 + M) * x1 + 30 * x_canoe, where x1 is Ricardo's position and x_canoe is the canoe's position. After they exchange seats, the new COM becomes (M + 80) * (x1 + 3) + 30 * x_canoe. Given that the canoe moves 40 cm relative to a log during the exchange, the change in position allows for the calculation of Carmelita's mass. By setting the initial and final COM equations equal and solving for M, one can determine Carmelita's mass. The final calculation reveals that Carmelita's mass is approximately 60 kg.
suspenc3
Messages
400
Reaction score
0
Ricardoof mass 80Kg, and Carmelita, who is lighter, are enjoying Lake Merced at dusk in a 30Kg canoe. When the canoe is at rest in the placid water, they exchange seats, which are 3m apart and symmetrically located with respect to the canoe's centre. Ricardo notices that the canoe moves 40 cm relative to a submerged log during the exchange and calculates Carmelita's mass, which she has not told him. What is it?

I'm guessing that I should first find The COM of the canoe with the people in it. How can I do this with an unknown second mass?
 
Physics news on Phys.org
Lets say the unknown mass is M. write the expression for the center of mass with this variable. Write the expression for the center of mass in the new position. You know that they will be in the same place.
 
Thread 'Collision of a bullet on a rod-string system: query'
In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
Back
Top