Question 1.1

Corvette speeds up to 10mph quicklyGeneral Motors mistakenly calls this car fast. Fast has to do with the speed limit. Even if its only going 10 mi/hr, the Corvette does have an impressive acceleration.

2015 Chevy Corvette Z06

How quickly doesa Corvette get to 10mph?If the acceleration of a Corvette is 9m/(s*s), how quickly in seconds does it get to 10mph?a. 0.5; b. 1.0; c. 1.5; d. 2.0; e. none are close

Car and Driver

Create a step by step solution:SketchConvert to standard units: List the variables we know and want:Pick the physics equation:

Algebra:Arithmetic: Letter answer: Optional: Estimate the uncertainty. Comment on the numbers.60sec=1min1609m=1mi2.24mi/hr=1m/s0.0254m=1in

v=x/tBasic. (a isnt involved.) If needed, vave=(x-xo)/(t-to); vave=(v+vo)/2a=v/tBasic. (x isnt involved.) Often: a=(v-vo)/t; x=vo*t+at2/2Comes from Eqs. 1&2. Handy if no vv2=vo2+2axComes from Eqs. 3&4. Handy if no t.Step by step solution:Sketch

Convert v units: v=10[mi/hr]*[1m/s]/[2.24mi/hr]=4.5m/sPick the variables we know and want:vo, v, a, t=?Pick the equation:

v=10t=?v=x/tBasic. (a isnt involved.) If needed, vave=(x-xo)/(t-to); vave=(v+vo)/2a=(v-vo)/tBasic. (x isnt involved.); x=vo*t+at2/2Comes from Eqs. 1&2. Handy if no vv2=vo2+2axComes from Eqs. 3&4. Handy if no t.

Slope=a=9.08m/s*sStep by step answer continued5. Algebra:t=(v-vo)/aArithmetic: t=(4.5m/s-0)/9.08(m/s2) =0.50sAnswer: a.

Comment: The GM ad person is confused about the difference between speed and acceleration. In this test the car doesnt show high speed, but the quick increase in speed shows a big value of acceleration and that reflects the powerful engine compared to the cars mass: F=ma