WORLD FOR CIVIL

Statics & Strength of Materials

Topic 6.4c - Problem Assignment 3 - Torsion

1. A 3/4 inch diameter steel shaft has a 6 inch diameter pulley attached. The belt on the pulley has a tensile force of 65 pounds on one side and 35 pounds on the other side? Determine the torque applied to the shaft. Determine the power transmitted by the pulley if the shaft is turning at 1200 rpms.

2. A V-belt is attached to a 6 inch diameter pulley. The belt tension on the two sides of the pulley are 60 pounds and 100 pounds. Determine the torque applied to the pulley by the V-belt. Determine the power transmitted by the shaft if it is rotating at 600 rpms.

3. A propeller is attached to the drive shaft of an outboard by means of a brass shear pin. The pin is has an ultimate shear strength of 23,000 psi. Determine the maximum torque that can be transmitted if the shaft is 3/4 inch in diameter and the pin is 1/4 inch in diameter.

4. Two rotating shafts are connected with gears. The first shaft has an 8 inch gear with 40 teeth and the second shaft has a 5 inch gear with 25 teeth. The first shaft is rotating at 300 rpms. Determine the rotational speed of the second shaft.

5. Consider the shafts and gears in problem 4. The teeth of the gear on the first shaft push on the teeth of the gear on the second shaft. These forces are equal and opposite. If this force is 120 pounds, determine the torques acting on each of the two shafts.

6. Determine the power transmitted by the torques in each of the two shafts in the problems above.

7. The chain ring on a bicycle has 42 teeth and the free wheel has 28 teeth. A force of 150 pounds is applied to the 7 inch peddle arm. The chain ring has 3 teeth per inch.

1. Determine the torque delivered to the chain ring.
2. Determine the force in the chain.
3. Determine the torque delivered to the free wheel.
4. Determine the power delivered if the free wheel rotates at 90 rpms.
   

8. The chain ring on a bicycle has 42 teeth and the free wheel has 15 teeth. A force of 150 pounds is applied to the 7 inch peddle arm. The chain ring has 3 teeth per inch.

1. Determine the torque delivered to the chain ring.
2. Determine the force in the chain.
3. Determine the torque delivered to the free wheel.
4. Determine the power delivered if the free wheel rotates at 90 rpms.