An airplane travels 2100 km at a speed of 720 km/h and  then encounters a tailwind that boosts its speed to 990 km/h for the next 2800 km. What was the total time for the trip? What was the average speed of the plane for this trip?[Hint: Does Eq. 2–11d apply?

(II) A stone is thrown vertically upward with a speed of 24.0 m/s(a) How fast is it moving when it is at a height of 13.0 m? (b) How much time is required to reach this height? (c) Why are there two answers to (b)?

You drive 4.00 mi at 30.0 mi>h and then another 4.00 mi at 50.0 mi>h. (a) Is your average speed for the 8.00-mi trip greaterthan, less than, or equal to 40.0 mi>h? (b) Which of the following is the best explanation for your prediction?I. The average of 30.0 mi>h and 50.0 mi>h is 40.0 mi>h, and hence this is the average speed for the trip.II. You go farther during the 50.0 mi>h part of the trip, and hence your average speed is greater than 40.0 mi>h.III. You spend more time during your trip traveling at 30.0 mi>h, and hence your average speed is less than 40.0 mi>h.

(II) An athlete performing a long jump leaves the ground at a 27.0° angle and lands 7.80 m away. (a) What was the takeoff speed? (b) If this speed were increased by just 5.0%, how much longer would the jump be?

37. (III) A stunt driver wants to make his car jump over 8 cars parked side by side below a horizontal ramp (Fig. 3–41). (a) With what minimum speed must he drive off the hori- zontal ramp? The vertical height of the ramp is 1.5 m above the cars and the horizontal distance he must clear is 22 m. (b) If the ramp is now tilted upward, so that “takeoff angle" is 7.0° above the horizontal, what is the new minimum speed? 22 m -1.5 m - Must clear this point! AAA. FIGURE 3-41 Problem 37.

(II) Extreme-sports enthusiasts have been known to jump off the top of El Capitan, a sheer granite cliff of height 910 m in Yosemite National Park. Assume a jumper runs horizontally off the top of El Capitan with speed 4.0 m/s and enjoys a free fall until she is 150 m above the valley floor, at which time she opens her parachute (Fig. 3–37). (a) How long is the jumper in free fall? Ignore air resis- tance. (b) It is important to be as far away from the cliff as possible before opening the parachute. How far from the cliff is this jumper when she opens her chute? 4.0 m/s 910 m 150 m FIGURE 3-37 Problem 26.

A baseball player throws a ball into the air with an initial speed of 27 m/s [up]. Ignore air resistance. (a) How high does the ball go? (b) How long is the ball in the air before she catches it? do this using GRASS eqaution

(II) Every year the Earth travels about 109 km as it orbits the Sun. What is Earth’s average speed in km/h

The magnitude of average velocity is always ……to the average speed. equal Less Greater than Less than