Constants Part A Mary and Sally are in a foot race (see figure (Figure 1)). When Mary is 22 m from the finish line, she has a speed of 4.0 m/s and is 5.0 m behind Sally, who has a speed of 5.0 m/s. Sally thinks she has an easy win and so, during the remaining portion of the race, decelerates at a constant rate of 0.46 m/s2 to the finish line What constant acceleration does Mary now need during the remaining portion of the race, if she wishes to cross the finish line side- by-side with Sally? Express your answer using two significant figures. View Available Hint(s) 2 m/s Submit Figure 1 of 1 Provide Feedback Next > Finish Mary Sally 4.0 m/s5.0 m/s 5,0 m 22 m Pearson

An Olympic-class sprinter starts a race with an acceleration of 4.50 m/s2. (a) What is her speed 2.40 s later? (b) Sketch a graph of her position vs. time for this period.

An airplane leaves Chicago and makes the 3000-km trip Los Angeles in 5.0 h. A second plane leaves Chicago one-half hour later and arrives in Los Angeles at the same time. Compare the average velocities of the two planes. Ignore the curvature of Earth and the difference in altitude between the two cities.

Consider the velocity vs. time graph of a person in an elevator shown in Figure 2.58. Suppose the elevator is initially at rest. It then accelerates for 3 seconds, maintains that velocity for 15 seconds, then decelerates for 5 seconds until it stops. The acceleration for the entire trip is not constant so we cannot use the equations of motion from Motion Equations for Constant Acceleration in One Dimension for the complete trip. (We could, however, use them in the three individual sections where acceleration is a constant.) Sketch graphs of (a) position vs. time and (b) acceleration vs. time for this trip.

A graph of v(t) is shown for a world-class track sprinter in a 100-m race. (See Figure 2.67). (a) What is y1his average velocity for the first 4 s? (b) What is his instantaneous velocity at t=5 s? (c) What is his average acceleration between 0 and 4 s? (d) What is his time for the race?

Unreasonable results A runner approaches the finish line and is 75 m away; her average speed at this position is 8 m/s. She decelerates at this point at 0.5m/s2 . How long does it take her to cross the finish line horn 75 m away? Is this reasonable?

Lisa in her Lamborghini accelerates at (3.00i2.00j)m/s2, while Jill in her Jaguar accelerates at (1.00i3.00j)m/s2. They both start from rest at the origin. After 5.00 s, (a) what is Lisas speed with respect to Jill. (b) how far apart are they, and (c) what is Lisas acceleration relative to Jill?

In 1967, New Zealander Burt Munro set the world record for an Indian motorcycle, on the Bonneville Salt Flats in Utah, of 295.38 km/h. The one-way course was 8.00 km long. Acceleration rates are often described by the time it takes to reach 96.0 km/h from rest. If this time was 4.00 s and Burt accelerated at this rate until he reached his maximum speed, how long did it take Burt to complete the course?

Parts (a), (b), and (c) of Figure 2.10 represent three graphs of the velocities of different objects moving in straight-line paths as functions of time. The possible accelerations of each object as functions of time are shown in parts (d), (c), and (f). Match each velocity vs. time graph with the acceleration vs. time graph that best describes the motion. Figure 2.10 (Quick Quiz 2.3) Match each velocity vs. time graph to its corresponding acceleration vs. time graph.

An object that is thrown straight up falls back to Earth. This is one-dimensional motion. (a) When is its velocity zero? (b) Does its velocity change direction? (c) Does the acceleration clue to gravity have the same sign on the way up as on the way clown?