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OCTOBER 24, 2017 PHYSICS 5 FATION PROBLEM 2 Your friend has an old car that wont

ID: 1785690 • Letter: O

Question

OCTOBER 24, 2017 PHYSICS 5 FATION PROBLEM 2 Your friend has an old car that wont start. He asks you to push the car fast enough so that he might start it. You only have 100 m of road to accomplish this. Assume constant acceleration and that the car starts at rest. a. If the car will only start when it reaches a speed of 10 m/s how much Work (minimum amount possible) is your friend asking you to do? b. If the car will only start when it reaches a speed of 15 m/s how much Work (minimum amount possible) is your friend asking you to do?

Explanation / Answer

Applying work-energy theorem,
Work done = change in KE

(A) W = m (10^2 - 0 )/2 = 50m

(B) W = m (15^2 - 0) / 2 = 112.5 m

where m = mass of car

put m in kg then get W in Joule.