Quiz 15

1. A horizontal lever is pivoted at its mid-point. Which of the following forces will result in a positive torque?

A. An upward force upplied at the left end of the lever.
B. An upward force applied at the location of the pivot
C. A downward force applied at the location of the pivot.
D. A downward force applied at the left end of the lever.
E. A downward force applied at the right end of the lever

2. The principle of conservation of angular momentum states that...

A. the angular momentum of an object will be conserved if the net force acting on the object is a constant.
B. the angular momentum of an object will be conserved if all the forces acting on the object are conservative.
C. the angular momentum of an object will be conserved if the net torque acting on the object is zero.
D. the angular momentum of an object will be conserved if the net torque acting on the object is a constant.
E. the angular momentum of an object will be conserved if the net force acting on the object is zero.

3. A horizontal lever of length 2.4 m is pivoted at its mid-point. An downward force of 13 N is acting at the right end of the lever. Calculate the torque acting on the lever.

A. -18.215 N m
B. -15.6 N m
C. -12.157 N m
D. -3.846 N m
E. -6.303 N m

4. A horizontal lever of length 5.5 m is pivoted at its mid-point. A 25 N upward force (force with upward vertical component) that makes an angle of 60 deg with the horizontal-left is acting at a point 0.2 m away from the right end of lever. Calculate the torque acting on the lever.

A. 55.209 N m
B. 79.854 N m
C. 60.781 N m
D. 28.477 N m
E. 40.9 N m

5. A uniform horizontal lever of length 2.4 m is pivoted at its mid-point. The following forces are acting on the lever: a 5 N vertically downward force acting at the right end of the lever, a 0.43 N vertically downward force acting at the left end of the lever, and a 6 N vertically upward force acting at a point on the lever 0.3 m away from the left end. Calculate the net torque acting on the lever.

A. -5.84 N m
B. -12.207 N m
C. -10.884 N m
D. -17.904 N m
E. -2.575 N m

6. A uniform horizontal lever of length 3.2 m is pivoted at its mid-point. The following forces are acting on the lever: a 2 N upward force (force with upward vertical component) that makes an angle of 80 deg with the horizontal-left acting at the right end of the lever, a 9 N vertically downward force acting at the left end of the lever, and a 0.93 N vertically downward force acting at a point on the lever 0.6 m away from the right end. Calculate the net torque acting on the lever.

A. 7.025 N m
B.11.917 N m
C. 16.621 N m
D. 10.025 N m
E. 26.917 N m

7. A uniform horizontal lever of length 3.63 m is pivoted at its mid-point. A vertically downward force of 2.71 N is acting at the left end of the lever. Where in the lever should a 15.53 N vertically downward force be applied if the lever is to be in equilibrum?

A. 0.427 m to the left from the pivot
B. 0.317 m to the right from the pivot
C. 0.585 m to the right from the pivot
D. 0.585 m to the left from the pivot
E. 0.103 m to the left from the pivot

8. A uniform horizontal lever of length 5.2 m pivoted at its mid-point is in equilibrium. The following forces are acting on the lever: a 11 N downward force (force with downward vertical component) that makes an angle of 60 deg with the horizontal-left acting at the right end of the lever, an unknown vertically downward force acting at the left end of the lever, and a 5 N vertically downward force acting at a point on the lever 0.8 m away from the right end. Calculate the magnitude of the unknown force.

A. 22.487 N
B. 7.264 N
C. 10.187 N
D. 12.988 N
E. 16.6 N

9. Three particles of masses 9 kg, 9 kg and 8 kg are located at the points ( 15, 5 ) m, ( 16, -2 ) m, and ( 17, -1 ) m respectively. Determine the location of the center of gravity of the three particles.

A. (1.707, 1.067) m
B. (15.962, 1.219) m
C. (15.962, 1.219) m
D. (7.06, 0.731) m
E. (15.962, 0.731) m

10. The center of gravity of two particles of masses 2.34 kg and 3 kg is located at the point ( 1, 4 ) m. The 2.34 kg particle is located at the point ( -5, -5 ) m. Find the location of the 3 kg particle.

A. ( 7.252, 7.389 ) m
B. ( 5.68, 7.389 ) m
C. ( 4.963, 20.183 ) m
D. ( 7.252, 11.02 ) m
E. ( 5.68, 11.02 ) m

Quiz 15: