Physics 111 Practice Problem Statements 02 Motion in One Dimension SJ 8th Ed.: Ch. 2.1 – 2.8 Contents: 2-1E, 2-5E, 2-9P, 2-13P, 2-33P, 2-36P* 2-41E, 2-49P*, 2-55P, 2-59P* Extra: 2-34P Introduction to motion & kinematics, definitions Position and Displacement Average velocity, average speed Instantaneous velocity and speed Acceleration Motion diagrams Constant acceleration - a special case Kinematic equations Free fall Another look at constant acceleration (kinematic equations derived using calculus). 8/8/2011

Problem 2-1E: If a baseball pitcher throws a fastball at a horizontal speed of 160 km/h, how long does the ball take to reach home plate 18.4 m away? 8/8/2011

Problem 2-5P: You drive on Interstate 10 from San Antonio to Houston, half the time at 55 km/h and the other half at 90 km/h. On the way back you travel half the distance at 55 km/h and the other half at 90 km/h. What is your average speed (a) from San Antonio to Houston, (b) from Houston back to San Antonio, and (c) for the entire trip? (d) What is your average velocity for the entire trip? (e) Sketch x versus t for (a), assuming the motion is all in the positive x direction. Indicate how the average velocity can be found on the sketch. 8/8/2011

Problem 2- 9P: On two different tracks, the winners of the one-kilometer race ran their races in 2 min, 27.95 s and 2 min, 28.15 s. In order to conclude that the runner with the shorter time was indeed faster, how much longer can the other track be in actual length? 8/8/2011

Problem 2- 13P: How far does the runner whose velocity–time graph is shown in Fig. 2-18 travel in 16 s? 8/8/2011

Problem 2- 33P: A car traveling 56. 0 km/h is 24 Problem 2- 33P: A car traveling 56.0 km/h is 24.0 m from a barrier when the driver slams on the brakes. The car hits the barrier 2.00 s later. (a) What is the car's constant deceleration before impact? (b) How fast is the car traveling at impact? 8/8/2011

Problem 2- 36P*: At the instant the traffic light turns green, an automobile starts with a constant acceleration a of 2.2 m/s2. At the same instant a truck, traveling with a constant speed of 9.5 m/s, overtakes and passes the automobile. (a) How far beyond the traffic signal will the automobile overtake the truck? (b) How fast will the car be traveling at that instant? 8/8/2011

Problem 2- 41: At a construction site a pipe wrench struck the ground with a speed of 24 m/s. (a) From what height was it inadvertently dropped? (b) How long was it falling? (c) Sketch graphs of y, v, and a versus t for the wrench. 8/8/2011

Problem 2- 49P*: A key falls from a bridge that is 45 m above the water. It falls directly into a model boat, moving with constant velocity, that is 12 m from the point of impact when the key is released. What is the speed of the boat? 8/8/2011

Problem 2- 55P: Water drips from the nozzle of a shower onto the floor 200 cm below. The drops fall at regular (equal) intervals of time, the first drop striking the floor at the instant the fourth drop begins to fall. Find the locations of the second and third drops when the first strikes the floor. 8/8/2011

Problem 2- 59P*: A hot-air balloon is ascending at the rate of 12 m/s and is 80 m above the ground when a package is dropped over the side. (a) How long does the package take to reach the ground? (b) With what speed does it hit the ground? 8/8/2011

Problem 2- 34P: A red train traveling at 72 km/h and a green train traveling at 144 km/h are headed toward one another along a straight, level track. When they are 950 m apart, each engineer sees the other's train and applies the brakes. The brakes decelerate each train at the rate of 1.0 m/s2. Is there a collision? If so, what is the speed of each train at impact? If not, what is the separation between the trains when they stop? 8/8/2011