sol04 - The Dodge Caravan has the higher final speed even...

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PHYSICS 103 Chapter 2 -- HW #4 Questions 32. Because the time intervals are the same, we do not actually have to calculate the average accelerations to be able to answer the question. The animal with the largest change in velocity has the larger acceleration. The change in velocity for the jaguar is 30 mph – 0 = 30 mph, and that for the cheetah is 45 mph – 20 mph = 25 mph. Therefore, the jaguar has the larger acceleration. Don’t be fooled by the fact that the cheetah has the faster final speed. 34. The Ford Taurus has an acceleration of 1(mph) per second. Therefore, it gains 1 mph for each of the 10 seconds. Therefore, it gains 10 mph. Because it started with a speed of 50 mph, its final speed is 55 mph + 10 mph = 65 mph. The Dodge Caravan has an acceleration of 2 (mph) per second. Therefore, it gains 2 mph for each second for a total of 20 mph. Its final speed is 50 mph + 20 mph = 70 mph.
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Unformatted text preview: The Dodge Caravan has the higher final speed even though it had the smaller initial speed. Exercise 16. We obtain this result by using our definition of the average acceleration. The important thing is the change in velocity, not the individual velocities. 120 km/h 0 km/h km/h 6 20 s s v a t ∆-= = = ∆ Problem 20. (a) The definition for the average acceleration is the change in velocity divided by the time taken. Therefore, 69 mph 0 mph mph 3.56 19.4 s s v a t ∆-= = = ∆ Because the car is speeding up, the direction of the acceleration is the same as that of the final velocity. (b) The definition of the average speed is the distance traveled divided by the time taken. Therefore, 0.25 miles 0.0129 miles/s 19.4 s d s t = = = Because this number is hard to interpret, let’s convert it to mph. miles 3600 s 0.0129 46.4 mph s 1 h = ÷...
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This document was uploaded on 10/29/2011 for the course PHSX 103 at MSU Bozeman.

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