# Chapter 2 (1-26)

**Flashcard maker :**Paulina Ratliff

1.) **gj newsha ** The space shuttle travels at a speed of about 7.6 x 10^3 m/s. The blink of an astronaut’s eye lasts about 110ms. How many football fields (length = 91.4m) does the shuttle cover in the blink of an eye?

2.) **gj newsha** For each of the tree pairs of positions listed in the following table, determine the magnitude and direction (positive or negative) of the displacement.

3.) **gj newsha** Due to continental drift, the North American and European continents are drifting apart at an average speed of about 3 cm per year. At this speed, how long (in years) will it take for them to drift apart by another 1500m (a little less than a mile)?

4.) **gj newsha** You step onto a hot beach with your bare feet. A nerve impulse generated in your foot, travels through your nervous system at an average speed of 110 m/s. How much time does it take for the impulse, which travels a distance of 1.8m, to reach your brain?

5.) **gj newsha** The data in the following table describe the initial and final positions of a moving car. The elapsed time for each of the three pairs of positions listed in the table is 0.50s. Review the concept of average velocity in Section 2.2 and then determine the average velocity (magnitude and direction) for each of the three pairs. Note that the algebraic sign of your answers will convey the direction.

answers:

(a) +8 m/s

(b) -8 m/s

(c) +20 m/s

(a) +8 m/s

(b) -8 m/s

(c) +20 m/s

6.) **gj newsha** One afternoon, a couple walks three-fourths of the way around a circular lake, the radius of which is 1.50 km. They start at the west side of the lake and head due south to begin with. (a) What is the distance they travel? (b) What are the magnitude and direction (relative to due east) of the couple’s displacement?

7.) **gj newsha** The three-toed sloth is the slowest-moving land mammal. On the ground, the sloth moves at an average speed of 0.037 m/s, considerably slower than the giant tortoise, which walks at 0.076 m/s. After 12 minutes of walking, how much further would the tortoise have gone relative to the sloth?

8.) **gj newsha** An 18-year old runner can complete a 10.0-km course with an average speed of 4.39 m/s. A 50-year-old runner can cover the same distance with an average speed of 4.27 m/s. How much later (in seconds) should the younger runner start in order to finish the course at the same time as the older runner?

9.) **gj newsha** A tourist being chased by angry bear is running in a straight line toward his car at a speed of 4.0 m/s. The car is a distance d away. The bear is 26m behind the tourist and running at 6.0 m/s. The tourist reaches the car safely. What is the maximum possible for d?

10.) *** **ask ney**In reaching her destination, a backpacker walks with an average velocity of 1.34 m/s, due west. This average velocity results because she hikes for 6.44 km with an average velocity of 2.68 m/s, due west, turns around, and hikes with an average velocity of 0.447 m/s, due east. How far east did she walk?

11.) **gj newsha** A bicyclist makes a trip that consists of three parts, each in the same direction (due north) along a straight road. During the first part, she rides for 22 minutes at an average speed of 7.2 m/s. During the second part, she rides for 36 minutes at an average speed of 5.1 m/s. Finally, during the third part, she rides for 8.0 minutes at an average speed of 13 m/s. (a) How far has the bicyclist traveled during the entire trip? (b) What is her average velocity for the trip?

12.) **practice** A car makes a trip due north for three-fourths of the time and due south one-fourth of the time. The average northward velocity has a magnitude of 27 m/s, and the average southward velocity has a magnitude of 17 m/s. What is the average velocity (magnitude and direction) for the entire trip?

13.) **gj newsha** **review again** You are on a train that is traveling at 3.0 m/s along a level straight track. Very near and parallel to the track is a wall that slopes upward at 12 degree angle with the horizontal. As you face the window (0.90m high, 2.0m wide) in your compartment, the train is moving to the left, as the drawing indicates. The top edge of the wall first appears at window corner A and eventually disappears at window corner B. How much time passes between appearance and disappearance of the upper edge of the wall?

14.) **gj newsha** A car is traveling to the left, which is the negative direction. The direction of travel remains the same throughout the problem. The car’s initial speed is 27.0 m/s, and during a 5.0-s interval, it changes to a final speed of (a) 29.0 m/s and (b) 23.0 m/s. In each case, find the acceleration (magnitude and algebraic sign) and state whether or not the car is decelerating.

15.) *go over again* (a) Suppose that a NASCAR race car is moving to the right with a constant velocity of +82 m/s. What is the average acceleration of the car? (b) Twelve seconds later, the car is halfway around the track and traveling in the **opposite direction** with the same speed. What is the average acceleration of the car?

16.) **gj newsha** Over a time interval of 2.16 years, the velocity of a planet orbiting a distance star reverses direction, changing from +20.9 km/s to -18.5 km/s. Find (a) the total change in the planet’s velocity (in m/s) and (b) its average acceleration (in m/s^2) during this interval. Include the correct algebraic sign with your answers to convey the directions of the velocity and the acceleration.

17.) **gj newsha** A motorcycle has a constant acceleration of 2.5 m/s^2. Both the velocity and acceleration of the motorcycle point in the same direction. How much time is required for the motorcycle to change its speed from (a) 21 to 31 m/s, and (b) 51 to 61 m/s?

18.) **gj newsha** A sprinter explodes out of the starting block with an acceleration of +2.3 m/s^2, which she sustains for 1.2s. Then, her acceleration drops to zero for the rest of the race. What is her velocity (a) at t = 1.2s, and (b) at the end of the race?

19.) *almost right* The initial velocity and acceleration of four moving objects at a given instant in time are given in the following table. Determine the final *speed* of each of the objects, assuming that the time elapsed since t= 0s is 2.0s.

20.) **review again** An Australian emu is running due north in a straight line at a speed of 13.0 m/s and slows down to a speed of 10.6 m/s in 4.0 s. (a) What is the direction of the bird’s acceleration? (b) Assuming that the acceleration remains the same, what is the bird’s velocity after an additional 2.0s has elapsed?

21.) **gj newsha** For a standard production car, the highest road-tested acceleration ever reported occured in 1993, when a Ford RS200 Evolution went from zero to 26.8 m/s (60 mi/h) in 3.275s s. Find the magnitude of the car’s acceleration.

22.) **youre understanding it, keep practicing** A car is traveling along a straight road at a velocity of +36.0 m/s when its engine cuts out. For the next twelve seconds the car slows down, and its average acceleration is a1. For the next six seconds the car slows down further, and its average acceleration is a2. The velocity of the car at the end of the eighteen-second period is +28.0 m/s. The ratio of the average acceleration is a1/a2 = 1.50. Find the velocity of the car at the end of the initial twelve-second interval.

23.) **practice one more time** Two motorcycles are traveling due east with different velocities. However, four seconds later, they have the same velocity. During this four-second interval, cycle A has an average acceleration of 2.0 m/s^2 due east, while cycle B has an average acceleration of 4.0 m/s^2 due east. By how much did the speed differ at the beginning of the four-second interval, and which motorcycle was moving faster?

24.) *you did fine, do again to get this problem cold* In getting ready to slam-dunk the ball, a basketball player starts from rest and sprints to a speed of 6.0 m/s in 1.5s. Assuming that the player accelerates uniformly, determine the distance he runs. – **good thinking, you account for acceleration first and then went with the appropriate equation.**

25.) **gj newsha** A jogger accelerates from rest to 3.0 m/s in 2.0s. A car accelerates from 38.0 to 41.0 m/s also in 2.0 s. (a) Find the acceleration (magnitude only) of the jogger. (b) Determine the acceleration (magnitude only) of the car. (c) Does the car travel farther than the jogger during the 2.0 s? If so, how much further?

26.) **gj newsha** A VW Beetle goes from 0 to 60.0 mi/h with an acceleration of +2.35 m/s^2. (a) How much time does it take for the Beetle to reach this speed? (b) A top-fuel dragster can go from 0 to 60.0 mi/h in 0.600 s. Find the acceleration (in m/s^2) of the dragster.