Homework Help: physics

Posted by Josh on Monday, December 10, 2012 at 7:00pm.

A brother (mass 20 kg) and his big sister (mass 32 kg) want to play on a teeter-totter. The beam is 7 m long and has a mass of 41 kg. Suppose the brother sits at the end of his side, 3.5 m away from the pivot point. How far away from the pivot point does the sister need to sit for the system to be in rotational equilibrium?

physics - Mila, Tuesday, April 16, 2013 at 11:37am
Use the center of mass fomula:
Xcm = (M1X1 + M2X2 + ... + MnXn)/(M1 + M2 + ... + Mn)
Don't forget the mass of the teeter-totter and its location at its geometric center (M1 = 41 kg, X1 = 3.5 since the fulcrum is in the middle of the beam).
Set the location of the sister at the origin (X = 0) and the brother at the opposite end of the beam (X = 7m).
Xcm = (20 x 7 + 32 x 0 + 41 x 3.5)/(20 + 32 + 41) = 283.5/93 = 3.05
The sister is 3.05 m from the pivot point.

Answer this Question

Related Questions

Physics please help!! - A school yard teeter totter with a total length of 5.46 ...
Physics - A child sits on one side of a teeter totter of length 7.60 m, a ...
Physics - A child sits on one side of a teeter totter of length 7.60 m, a ...
physics - Juggles the clown stands on one end of a teeter-totter at rest on the ...
physics - Two children are balancing on a teeter-totter. One child has a mass of...
physics - Two children are balancing on a teeter-totter. One child has a mass of...
Physics URGENT!!! - Gayle runs at a speed of 9.00 m/s and dives on a sled, ...
Physics URGENT!!! - Gayle runs at a speed of 9.00 m/s and dives on a sled, ...
Physical Science - I need help with this problem because it is confusing me. I ...
Physics URGENT!!! - Gayle runs at a speed of 9.00 m/s and dives on a sled, ...

For Further Reading

First Name:
School Subject:
Answer: