14.0

1-2. Two cars collide at an icy intersection and stick together afterward. The first car has a mass of 1200 kg and is approaching at 8.00 m/s due south. The second car has a mass of 850 kg and is approaching at 17.0 m/s 30^o north of west. Calculate the final velocity (magnitude and direction) of the cars. How much kinetic energy is lost in the collision?

3. If someone can throw a football at an average velocity of 50 mph, at what angle will the the football go the farthest (assuming no wind effects), and about how far will it go in yards. To go the furthest distance, how long will the football be in the air? How far will the football go at an angle of 15 degrees above horizontal, and how long will it be in the air?

4. Antiballistic missiles (ABMs) are designed to have very large accelerations so that they may intercept fast-moving incoming missiles in the short time available. What is the takeoff acceleration of a 10,000-kg ABM that expels 196 kg of gas per second at an exhaust velocity of 2.5010³ m/s?

5. A strut at a 60 degree angle has weight (W) hanging by a cable that passes over the strut and attaches to the ground making an angle of 30 degrees. Draw a free body diagram of the system.

7. What are the bolt or nut tightening torques for 1/4x20 grade 3, 1/2x13 grade 6, and 3/4x10 grade 3. How much pressure is needed to be applied with an 18" wrench to properly tighten them to proper torque values?

8. In terms of center of gravity, when will an automobile turn over?

9. Does the center of gravity have to be within a material? Can you think of an item where it isn't? What?

10. What was the definition for equilibrium?What is the difference between translational and rotational equilibrium?

11. Greater force potentially causing rotation can be applied through a longer moment arm, Would that explain why wrench lengths are proportional to bolt size? Would applied tightening force be roughly the same then?

12. If the force is applied to the end of a moment arm at an angle other than perpendicular, what can you say about the torque forces applied to cause rotational motion?

13. CCW torque is considered positive, why?Does it have to always be?

14. When is rotational equilibrium going to happen?

15. Where would you suspect the center of gravity of a 6' 2x4 is located?