A motorist traveling at a constant 15 m/s (54 km/h, or about 34 mi/h) passes a school crossing where the speed limit is 10 m/s (36 km/h, or about 22 mi/h). Just as the motorist passes the school-crossing sign, a police officer on a motorcycle stopped there starts in pursuit with constant acceleration 3.0 m/s2 . (a) How much time elapses before the officer passes the motorist? At that time, (b) what is the officer’s speed and (c) how far has each vehicle traveled?

A white automobile is traveling at a constant speed of 90km/h on a highway. The driver notices a red automobile 1.0km behind, traveling in the same direction. Two minutes later, the red automobile passes the white automobile. a) What is the average speed of the red automobile relative to the white?  b) What is the speed of the red automobile relative to the ground?

Graph below represents the force on a 12 kg air mass as it passes through a jet engine.  Immediately after entering the engine, the force is 9,039 N, and the force tapers linearly to zero once the air reaches the back of the engine 2.3 m later.  If the air enters the engine with velocity 252 m/s, what is its exit velocity? (Please answer to the fourth decimal place - i.e 14.3225)

PROBLEM 2.27 A girl is riding her bicycle. When she gets to a corner, she stops to get a drink from her water bottle. At that time, a friend passes by her, traveling at a constant speed of 10.0 m/s. 32. After 25 s, the girl gets back on her bike and travels with a constant acceleration of 2.5 m/s². How long does it take for her to catch up with her friend? c. 20.70 s d. 21.70 s а. 19.70 s b. 18.70 s 33. If the girl had been on her bike and rolling along at a speed of 1.5 m/s when her friend passed, what constant acceleration would she need to catch up with her friend in the same amount of time? c. 0.709 m/s² d. 0.609 m/s² а. 0.809 m/s² b. 0.909 m/s2

A steel wire connects two trains at rest on the same track. The wire will snapif it is stretched by as much as 1 percent. The trains begin to accelerate in such away that their velocities, as measured in the ground frame, are always equal.Eventually, the wire snaps. Explain carefully why this happens. How fast are thetrains moving when the wire snaps?

The elevator in an office building, starting from rest at the first floor, is accelerated 0.75 m/sec2 for 5 secs. It continues at constant velocity for 12 secs, more and is then stopped in 3 secs with constant deceleration. If the floors are 3.75 m apart, at what floor did the elevator stop?

You are called as an expert witness in a trial for a traffic violation. The facts are these: A driver slammed on his brakes and came to a stop with constant acceleration. Measurements of his tires and the skid marks on the pavement indicate that he locked his car’s wheels, the car traveled 192 ft before stopping, and the coefficient of kinetic friction between the road and his tires was 0.750. He was charged with speeding in a 45 mi>h zone but pleads innocent. What is your conclusion: guilty or innocent? How fast was he going when he hit his brakes?

PROBLEM 2.7 7. A train running at 80 kph decelerates at 3 m/min? for 18 minutes. Find the distance travelled within this period. а. 16.14 km c. 18.14 km 17 LECTURE NOTES IN ENGINEERING MECHANICS b. 17.14 km d. 19.14 km

4) You were leisurely flying your F-18 when you encounter an alien aircraft. The alien was flying at an altitude of 3 km while you were at an altitude of 600 m. You begin to increase your speed at a rate of 2.0 m/s?. You are traveling at a speed of 750 km/h at the instant when 0 = 45° and at the same instant the alien has a constant velocity of 1,500 km/h. a) Determine the velocity and acceleration vectors (in m/s and m/s², respectively) of the alien as observed by you. [Ans. to Check: VB/A = 208.4 įm/s] b) Determine the time rate of change of the vector r that is between you and the alien ship in m/s. In other words, find r. [Ans. to Check: i = 147.32 m/s] Hint: Do not forget about your ability to dot in different directions to eliminate variables from the equation. c) Calculate the angular velocity of the spaceship relative to you in rad/s. d) Determine the radial and angular accelerations in m/s? and rad/s². [Ans. to Check: ï = 4.86 m/s²] VB 3 km VA 600 m

2).A 5.18 g bullet moving at 672 m/s strikes a 715g wooden block at rest on a frictionless      surface. The bullet emerges with its speed reduced to 428m/s. Find the resulting speed      of the block.