Problem 6.42 Sam, whose mass is 80kg , takes off across level snow on his jet-po

Question

Problem 6.42 Sam, whose mass is 80kg , takes off across level snow on his jet-powered skis. The skis have a thrust of 170N and a coefficient of kinetic friction on snow of 0.1. Unfortunately, the skis run out of fuel after only 15s . Part A What is Sam's top speed? Express your answer to two significant figures and include the appropriate units. V=17 m/s Part B How far has Sam traveled when he finally coasts to a stop? Express your answer to two significant figures and include the appropriate units. S=Values Units

Explanation / Answer

friction force = 0.1*80*9.81 =78.48 N

net acceleration for 15 s = (170- 78.48)/80 =1.144 m/s^2

distance travelled during 15 s = (1.144*15^2)/2 =128.7 m

velocity after 15 s = 1.144*15 = 17.16 m/s

deacceleration after 15 s = 78.48 / 80 =0.981 /s^2

formula : v^2 = u^2 +2as , here v=0

distance travelled during deacceleration = 17.16^2 /(2*0.981) =150.0844 m

total distance= 150.0844 +128.7 = 278.7844 m

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