Posted by **Sara** on Tuesday, February 14, 2012 at 12:16am.

Pepper pulls a 20.0 kg object along the floor accelerating at 2 m/s/s, and μ = .2. How much work has he done while pulling the string 5.0 m? If it takes her 1.0 seconds, how much power has she used? If 1.0 kcal = 4184 J, and an Oreo has 50 kcal, how many Oreos did Pepper have to eat to get the above done?

- Physics -
**Henry**, Thursday, February 16, 2012 at 7:44pm
a. Wo = mg = 20kg * 9.8N/kg = 196 N. =

Wt. of object.

Fo = 196N @ 0 Deg. = Force of object.

Fp = 196*sin(0) = 0 = Force parallel to

floor.

Fv = 196*cos(0) = 196 N. = Force perpendicular to floor.

Fn = Fap - Fp - Fk = ma,

Fap - 0 - 0.2*196 = 20*2,

Fap -0 - 39.2 = 40,

Fap = 40 + 39.2 = 79.2 N. = Applied force.

W = Fap * d = 79.2*5 = 396 Joules.

b.P=Fap*V=79.2 * 5m/s=396 J/s=396 W.

c. 0.396kJ * 239cal/kJ = 94.64 cal.

Oreos = 94.64cal * 1 Oreo/50cal = 1.9.

NOTE: An oreo cookie cannot have 50kcal(50.000 cal). I used 50 cal. in my calulation.

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