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Sam, whose mass is 75kg, takes off across level snow on his jet-powered skis. The skis have a thrust of 200N and a coefficient of kinetic friction on snow of 0.10. Unfortunately, the skis run out of fuel after only10 s.

a. What is Sam鈥檚 top speed?

b. How far has Sam traveled when he finally coasts to a stop?

Short Answer

Expert verified

a). Sam's top speed is 16.90m/s

b). Sam traveled230.2m

Step by step solution

01

Step 1. Given Information

We have,

Mass m=75kg

The skis thrust of Fthrust=200N

Kinetic friction on snow is k=0.10

timet=10s

02

Part a). Step 2. Calculate the acceleration and top speed

First, we find the acceleration

Fx=FnetFthrust-ff=FnetFthrust-kmg=maa=Fthrust-ukmg75kga=200-0.10(75)(9.81)75a=1.69m/s2

Now, find the top speed

vf=vi+atvf=0+(1.69)(10s)vf=16.90m/ssincevi=0

03

Part b). Step 1. Calculate the total distance traveled

The ski exert a 200N of thrust force and cause an acceleration of a=1.69m/s2 for t=10s and reaching a top speed of vf=16.90m/s

The force acting on the ski after it accelerate is the kinetic energy, resolving forces under equilibrium, we got

Fy=0N-mg=0

N=mg (1)

Substitute Equation(1) in (2)

fk=kmg (2)

Fx=0Fnet-fk=0

Let compute for the acceleration, substitute Equation (2) to above equation

localid="1649522800356" ma-kmg=0a=kmgma=kga=0.109.81a=0.98m/s2

04

Part b). Step 2. Find the total distance

vf2=vi2+2axvf2=vi2+2ax2x2=vf2-vi22ax2=(16.90)-(0)2(0.90)x2=145.7m

xis only the distance traveled when the ski is coasting

localid="1649522949011" xf=x0+v0t+12at2x1=0+0(10)+12(1.69)(10)2=84.5m

Total distance traveled

xtotal=x1+x2xtotal=84.5+145.7xtotal=230.2m

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