Two children sit on the opposite sides of a seasaw at a playground, doing so in a way that causes the seasaw to balance perfectly horizontal. The child on the left is from the pivot.

What is the mass of the second child if she sits from the pivot?

A gymnast is practicing her balances on a long narrow plank supported at both ends. Her mass is . The long plank has a mass of .

Calculate the force the right support provides upward if she stands from the right end. Use gravity .

An object starts from rest and accelerates to an angular velocity of in three seconds under a constant torque of . How many revolutions has the object made in this time?

The moment of inertia of a long thin rod about its end is determined to be .

What is the new value if the mass and length of the rod are both reduced by a factor of ?

A meter stick is nailed to a table at one end and is free to rotate in a horizontal plane parallel to the top of the table. A force of is applied perpendicularly to its length at a distance from the nailed end.

Calculate the resulting angular acceleration experienced by the meter stick.

A meter stick is secured at one end so that it is free to rotate in a vertical circle. It is held perfectly horizontally, and released.

Calculate the instantaneous angular acceleration the moment it is released.

A man sits on the end of a long uniform metal beam of length . The man has a mass of and the beam has a mass of .

What is the magnitude of the net torque on the plank about the secured end of the beam? Use gravity .

A square of side lengths and mass is shown with possible axes of rotation.

Which statement of relationships among the moments of inertia is correct?

A wind catcher is created by attaching four plastic bowls of mass each to the ends of four lightweight rods, which are then secured to a central rod that is free to rotate in the wind. The four lightweight rods are of lengths , , , and .

Calculate the moment of inertia of the four bowls about the central rod. You may assume to bowls to be point masses.

A 0.18 m long wrench is used to turn the nut on the end of a bolt. A force of 85 N is applied downward to the end of the wrench, as shown in the figure. The angle between the force and the handle of the wrench is 65 degrees.

What is the magnitude and direction of the torque (around the center of the bolt) due to this force?