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1. A 2.0-kg mass sliding on a frictionless surface explodes into two 1.0-kg masses. After the explosion the velocities of the masses are: (1) 3.0 m/s north, and (2) 5.0 m/s 30 degrees north of east. What was the magnitude of the original velocity of the 2.0 kg mass?
3.1 m/s 3.9 m/s 3.5 m/s 2.8 m/s
2. Identical particles are placed at the 50-cm and 80-cm marks on a meter stick of negligible mass. This rigid body is then mounted so as to rotate freely about a pivot at the 0-cm mark on the meter stick. If this body is released from rest in a horizontal position, what is the angular speed of the meter stick as it swings through its lowest position?
4.2 rad/s 5.4 rad/s 4.6 rad/s 5.0 rad/s
3. A merry-go-round of radius R=2 m has a moment of inertia I = 250 kg m^2, and is rotating at 10 rpm. A child whose mass is 25 kg jumps onto the edge of the merry-go-round, just before impact moving directly toward the center at 6 m/s. The new angular speed (in rpm) of the merry-go-round is approximately:
10. 9. 8. 7.
4. A horizontal meter stick supported at the 50-cm mark has a mass of 500 g hanging from it at the 20-cm mark and a 300-g mass hanging from it at the 60-cm mark. Determine the position on the meter stick at which one would hang a third mass of 600 g to keep the meter stick balanced.
74 cm 70 cm 65 cm 86 cm
5. A body of mass 5 kg is suspended by a spring which stretches 10 cm when the mass is attached. It is then displaced downward an additional 5 cm and released. Its vertical position in meters as a function of time is approximately:
y = .10 sin 10t y = .10 cos 10t y = .10 cos (10t plus .1) y = .10 sin (10t plus 5)
6. A satellite circles planet Roton every 2.8 h in an orbit having a radius of 1.2 x 10^7 m. If the radius of Roton is 5.0 x 10^6 m, what is the acceleration due to gravity at the surface of the planet?
31 m/s^2 27 m/s^2 34 m/s^2 40 m/s^2
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