Question

PH-UY 1013: MECHANICS 11. A rod of length 2 m and mass 3 kg is free to swing around an axle located at one end, which is attached to the ceiling. The rod is pulled an angle 20° from the vertical and released. What is the initial angular acceleration imparted to the rod by gravity? (I = ML²/3 for a rod pivoting about its end.) a) 4.72 rad/s² b) 2.75 rad/s² c) 5.63 rad/s² d) 2.51 rad/s² e) 3.68 rad/s² 12. A spherical star with twice the mass of the Sun and radius equal 700,000 km collapses spherically. The final star has radius R = 30 km. If the star was initially spinning at an angular velocity of 2.5x10?? rad/s and no mass was lost during the collapse, it is finally rotating at an angular velocity of: a) 560 rad/s b) 766 rad/s c) 490 rad/s d) 340 rad/s e) 1360 rad/s 13. Assume that your arm can be idealized as two bars hinged at the elbow, as shown. Your bicep muscle is attached to your forearm at a distance x = 5 cm from your elbow. You hold a mass of 2 kg in your outstretched hand. If the length of your forearm is L = 45 cm and the mass of your forearm is 3 kg, then the force your bicep must exert on your forearm to support the mass is a) 250 N b) 573 N c) 309 N d) 397 N e) 485 N 14. A mass of 5 kg is attached to a spring with spring constant k = 125 N/m, which is itself attached to a wall. If the mass is pulled to a distance A from its equilibrium position and released, what is the minimum time at which the kinetic energy of the system is 1/8 the total energy? (Assume the surface to be frictionless.) a) 0.209 s b) 0.236 s c) 0.0723 s d) 0.157 s e) 0.105 s 15. The Earth is 81.25 times as massive as the Moon and the radius of the Earth is 3.668 times the radius of the Moon. If a simple pendulum has a frequency of 2 Hz on Earth, what will be its frequency on the Moon? a) 0.407 Hz b) 0.814 Hz c) 1.34 Hz d) 1.22 Hz e) 1.63 Hz

          PH-UY 1013: MECHANICS
11. A rod of length 2 m and mass 3 kg is free to swing around an axle located at one end, which is attached to the ceiling. The rod is pulled an angle 20° from the vertical and released. What is the initial angular acceleration imparted to the rod by gravity? (I = ML²/3 for a rod pivoting about its end.)
a) 4.72 rad/s² b) 2.75 rad/s² c) 5.63 rad/s² d) 2.51 rad/s² e) 3.68 rad/s²
12. A spherical star with twice the mass of the Sun and radius equal 700,000 km collapses spherically. The final star has radius R = 30 km. If the star was initially spinning at an angular velocity of 2.5x10?? rad/s and no mass was lost during the collapse, it is finally rotating at an angular velocity of:
a) 560 rad/s b) 766 rad/s c) 490 rad/s d) 340 rad/s e) 1360 rad/s
13. Assume that your arm can be idealized as two bars hinged at the elbow, as shown. Your bicep muscle is attached to your forearm at a distance x = 5 cm from your elbow. You hold a mass of 2 kg in your outstretched hand. If the length of your forearm is L = 45 cm and the mass of your forearm is 3 kg, then the force your bicep must exert on your forearm to support the mass is
a) 250 N b) 573 N c) 309 N d) 397 N e) 485 N
14. A mass of 5 kg is attached to a spring with spring constant k = 125 N/m, which is itself attached to a wall. If the mass is pulled to a distance A from its equilibrium position and released, what is the minimum time at which the kinetic energy of the system is 1/8 the total energy? (Assume the surface to be frictionless.)
a) 0.209 s b) 0.236 s c) 0.0723 s d) 0.157 s e) 0.105 s
15. The Earth is 81.25 times as massive as the Moon and the radius of the Earth is 3.668 times the radius of the Moon. If a simple pendulum has a frequency of 2 Hz on Earth, what will be its frequency on the Moon?
a) 0.407 Hz b) 0.814 Hz c) 1.34 Hz d) 1.22 Hz e) 1.63 Hz

PH-UY 1013: MECHANICS
11. A rod of length 2 m and mass 3 kg is free to swing around an axle located at one end, which is attached to the ceiling. The rod is pulled an angle 20° from the vertical and released. What is the initial angular acceleration imparted to the rod by gravity? (I = ML²/3 for a rod pivoting about its end.)
a) 4.72 rad/s² b) 2.75 rad/s² c) 5.63 rad/s² d) 2.51 rad/s² e) 3.68 rad/s²
12. A spherical star with twice the mass of the Sun and radius equal 700,000 km collapses spherically. The final star has radius R = 30 km. If the star was initially spinning at an angular velocity of 2.5x10?? rad/s and no mass was lost during the collapse, it is finally rotating at an angular velocity of:
a) 560 rad/s b) 766 rad/s c) 490 rad/s d) 340 rad/s e) 1360 rad/s
13. Assume that your arm can be idealized as two bars hinged at the elbow, as shown. Your bicep muscle is attached to your forearm at a distance x = 5 cm from your elbow. You hold a mass of 2 kg in your outstretched hand. If the length of your forearm is L = 45 cm and the mass of your forearm is 3 kg, then the force your bicep must exert on your forearm to support the mass is
a) 250 N b) 573 N c) 309 N d) 397 N e) 485 N
14. A mass of 5 kg is attached to a spring with spring constant k = 125 N/m, which is itself attached to a wall. If the mass is pulled to a distance A from its equilibrium position and released, what is the minimum time at which the kinetic energy of the system is 1/8 the total energy? (Assume the surface to be frictionless.)
a) 0.209 s b) 0.236 s c) 0.0723 s d) 0.157 s e) 0.105 s
15. The Earth is 81.25 times as massive as the Moon and the radius of the Earth is 3.668 times the radius of the Moon. If a simple pendulum has a frequency of 2 Hz on Earth, what will be its frequency on the Moon?
a) 0.407 Hz b) 0.814 Hz c) 1.34 Hz d) 1.22 Hz e) 1.63 Hz

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