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III Careful measurements have been made of Olympic sprinter in the 100 meter dash. A quite realistic model is that the sprinter's velocity is given by
where t is in s, vxis in m/s, and the constants a and b are characteristic of the sprinter. Sprinter Carl Lewis's run at the 1987 World Championships is modeled with a = 11.81 m/s and
- What was Lewis's acceleration at t = 0 s, 2.00 s, and 4.00 s?
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Chapter 2 Solutions
Physics for Scientists and Engineers: A Strategic Approach, Vol. 1 (Chs 1-21) (4th Edition)
- A garden snail named Archie, owned by Carl Branhorn of Pott Row, England, covered a 33-cm course in 2.0 min at the 1995 World Snail Racing Championships, held in Longhan, England (Fig. P1.13). Determine Archies average speed Sav = d/t in the appropriate SI units.arrow_forwardThe speed S (m/mii) of an object is defined by S = 6t² + 2t + 3 after t minutes. For the first one minute, the object travelled for 10 m. Determine how far the object travelled for the first two minutes. O 25 O 40 O 20 O 30arrow_forwardAn automobile traveling 95 km/hkm/h overtakes a 1.40 kmkm -long train traveling in the same direction on a track parallel to the road. A) If the train's speed is 75 km/hkm/h, how long does it take the car to pass it in minutes? Express your answer to two significant figures and include the appropriate units. B) How far will the car have traveled in this time? Express your answer to two significant figures and include the appropriate units. C) How long does it take the car to pass the train if the car and train are traveling in opposite directions in minutes? Express your answer to two significant figures and include the appropriate units. D) How far will the car have traveled in this time? Express your answer to two significant figures and include the appropriate units.arrow_forward
- Mario rides his motorcycle in going to school. He drives at an average speed of 30 kilometers per hour. The distance between his house and the school is 15 kilometers. Every time he sees his best friend Jessica walking on the road, he invites her for a ride and lowers his speed. On the other hand, he increases his speed when he wakes up late for school. a) If x represents the time it takes Mario to drive to school with the given distance of 15 kilometers, how will you represent the relationship of his speed (y) versus the time (x)?arrow_forwardDanny takes his dog to the local dog park every morning, as well (dog-walking is very popular in this area). He walks with his dog 6 blocks east, 6 blocks north, and 6 west in order to get to the park. If each block is 50 meters, what distance did Danny travel in meters? Answer: marrow_forwardThe acceleration of an object (in m/s2) is given by the function a ( t ) = 5 sin ( t ). The initial velocity of the object is v ( 0 ) = − 9 m/s. Round your answers to four decimal places. a) Find an equation v(t) for the object velocity. b) Find the object's displacement (in meters) from time 0 to time 3. c) Find the total distance traveled by the object from time 0 to time 3.arrow_forward
- The velocity of a particle is defined as v(t) = {0.8t²i + 12t¹/2j+5k} m/s. Determine the magnitude of the particle's acceleration when t = 2 s. Express your answer to three significant figures and include the appropriate units. a = Submit Part B α= Submit Part C Value B = Determine the coordinate direction angle a of the particle's acceleration when t = 2 s. Express your answer in degrees to three significant figures. HÅ Submit Part D Request Answer Y = VE ΑΣΦ ↓↑ Request Answer Units Determine the coordinate direction angle of the particle's acceleration when t = 2 s. Express your answer in degrees to three significant figures. [5] ΑΣΦ Request Answer vec VE ΑΣΦ | 1 ? vec ? vec Review Determine the coordinate direction angle y of the particle's acceleration when t = 2 s. Express your answer in degrees to three significant figures. ? ?arrow_forwardA walker sees a rock fall from the top of a steep cliff and notices that it takes 1.5 seconds for the rock to fall the final third ( or 1/3) of the way. a) What is the height of the cliff in meters? b) In part (a) you get two roots to a quadratic equation and use one of them for your answer. What does the second root represent?arrow_forwardFigure 1 shows the velocity-time graph of a person moving along one straight path called the x-axis. When a timer starts to click (t = 0), the person is at x = 0. The whole journey lasts 20 seconds. v (m/s) 2 0 -2 0 4 8 2 12 16 t(s) 20 Figure 1: The velocity-time graph to go with Q1.6 Consider the first half of the journey from t = 0 to t = 10 seconds. Find the position of the person at t = 10 s and the average velocity between t= 0 and 10 seconds. (b) Identify the time windows during which the person has an non-zero acceleration and find the accelerations in those time windows. (c) For the whole journey from t = 0 to t = 20 s, find the position of the person at t = 20 s and the average velocity.arrow_forward
- My question isn't how to solve the problem exactly. In fact, it's already been solved on this website. My question is about the acceleration. When I solve this problem myself, first I calculate the velocity by dividing 100m by 53s. I get 1.89m/s. Then I use that to find the acceleration using the equation vf = vi + at. That's 1.89/53 = 0.036m/s^2. That's not correct. The correct way to find the acceleration is to us the equation d = 1/2 at^2 and solve that way without taking the intermediate step of finding the velocity. Doing it that way, the acceleration is 0.0712m/s^2. My question is why you get a different result doing it the first way than you get doing it the second way.arrow_forwardA car starts moving at time t=0 and goes faster and faster. Its velocity is shown in the following table. t (seconds) 0 3 6 9 12 Velocity (ft/sec) 0 8 27 43 74 A. Estimate how far the car traveled during the first 12 seconds using the left-hand sums with 4 subdivisions. Answer: B. Now estimate how far the car traveled during the first 12 seconds using the right-hand sums with four subdivisions. Answer:arrow_forwardScenario: A family drove home after visiting the father's family. From their relatives' home in Sendai, the car left for Tokyo, where they live. The graph below shows the car's travel. Car Travel from Sendai to Tōkyō 350 320 320 300 300 250 225 200 150 80 100 40 50 1 2 3 4 Time (hrs) 1. Compute for the car's velocity (in m/s) and acceleration (in m/s³) between one (1) and four (4) hours of travel. 2. Create a time-velocity graph for the car based from the given graph above. Distance (km)arrow_forward
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning