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Physics - Questions on Momentum

1. If a person pushed on a door with a force of 650 N and a moment arm of 0.75 meters, what would be the moment created?

2. A defensive lineman (mass = 88.5kg) is running at 12 m/s, and a linebacker (mass = 84kg) is running at 13.2 m/s. Determine which player has the greater linear momentum, and by how much.

3. The moment of inertia about the center of mass of a 4 kg segment is 1.2 kgm2. If the moment of inertia about the segment's proximal end is 3.3 kgm2, what is the distance between the proximal end and the center of mass?

4. A gymnast takes off in a layout position with an angular momentum of 42 kgm2/s. She tucks as she begins her somersault. What will be the magnitude of change in angular velocity as her moment of inertia changes from the layout (IL = 9.2 kgm2) to the tuck (IT = 3.8 kgm2)?

5.How far out from an axis must a 1200N force be applied (i.e., what is the forces moment arm) in order to counter and hold a 90Nm torque acting in the clockwise direction?

Solution Preview

(1) Moment created = Force * Moment arm = 650 N * 0.75 m = 487.50 Nm

(2) Lineman:

M = Mass * Velocity = 88.5 kg * 12 m/s = 1062 kg m/s


M = Mass * Velocity = 84 kg * 13.2 m/s = 1108.8 kg ...

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