North Carolina A&T; State University ring 2017 Friday, March 17 Physics 241 sec.

Question

North Carolina A&T; State University ring 2017 Friday, March 17 Physics 241 sec. 04 General Physics I Test 3 Chapters 7-9 r. R. Lee Ponting Your Name ach problem is worth 25 points. e sure to show some of your work (setup) on each problem ote, use an acceleration due to gravity of 9.8 m/sec for calculations below 8 m/sec. It then An fashioned" rollercoaster c of mass is pulled up 15 hill, force present. rolls old then continues on level ground" wi no frictional down the track to the bottom and m 00 kg a) How much Total Energy does the 100 kg car have at the top of the hi Vo 8m/s 15 m E(top) b) What will be the speed of the car at the bottom of the h speed bottom c) Suppose that in going down the hill, the car loses 3000 J to various frictional forces. What would the speed of th car at the bottom be now? speed after 2. a) In an Ideal Horizontal spring system, a 3 kg mass is pulled back x 35 cm and forth by a spring with no frictional loss in the system. If the spring has a constant of 1200 N/m, and is initially 3 kg pulled back a distance of 35 cm at this point? How much energy is stored in the system center point Energy spring is not center point" (x 0), where the yhr

Explanation / Answer

Initila speed u = 8 m/s

Height of the hill h = 15 m

mass m = 100 kg

Total energy E = mgh + (1/2) mv 2

= (100x9.8x15)+(0.5x100x8 2 )

= 17900 J

(b).Speed of the car at the bottom v = ?

From the relation v 2 - u 2 = 2gh

v 2 =u 2 + 2gh

= 8 2 +(2x9.8x15)

= 358

v = 18.92 m/s

(c).Kinetic energy at bottom K = E - 3000 J

= 17900 -3000 = 14900

i.e., (1/2)mV 2 = 14900

V 2 = (2x14900) / m

= 298

V = 17.26 m/s

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