I need help problem 2 omework should follow the documentation standards outline

Question

I need help problem 2

omework should follow the documentation standards outline for this class. All work must be done in encil and on engineering paper. A change in temperature of 20 C occurred. What is this change in Kelvin? 2, A car accelerates up a hill. W of the car = 4000 lbf. The car accelerates from 45 MPH to 70 MPH. (The driver just came out of a construction zone.) The straight stretch of road is 800 yards long and makes an 8 angle with the horizontal. Find the total work done by the car's motor. 3. Problem 6.11 on page 223 of your text. 4. Problem 6.39 on page 226 of your text.

Explanation / Answer

The work done will be:

W = change in KE + PE at the top

Change in KE = 1/2 m (v2^1 - v1^2)

v1 = 45 mph = 20.11 m/s; v2 = 70 mph = 31.3 m/s ; W = 4000 lbf = 17792.89 N ; x = 800 y = 731.5 m

m = 17792.89/9.81 = 1813.72

Ke = 0.5 x 1813.75 (21.3^2 - 20.11^2) = 521705 J

PE = m g h = 1813.75 x 9.81 x 731.5 x sin8 = 1811407 J

W = 521705 + 1811407 = 2333112 J

Hence, W = 2333112 J

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