Physics Problem Solving: Calculating Forces, Work, and Friction, Study notes of Physics

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Which problem should I work next?

A. 3-

B. 4-

C. 4-

D. 4-

E. 5-

Starting with 5-

6-67 How much power is needed to push a 50 kg chest at 0.8 m/s along a horizontal floor where the coefficient of friction is 0.25? Express your answer using two significant figures. How much work is done in pushing the chest 13 m? Clicker Estimate your power consumption as you do deep knee-bends at 1 /second 6-40 In midday sunshine, solar energy strikes Earth at the rate of about 1 ( kW/m^2). (a) How long would it take a perfectly efficient solar collector of 15 m^2 area to collect 40 kW- h of energy? Note: This is roughly the energy content in a gallon of gasoline. 5-48 A 300-g paperback book rests on a 1.2-kg textbook. A force is applied to the textbook, and the two books accelerate together from rest to 1 m/s in 0.5 s. The textbook is then brought to a stop in 0.33 s, during which time the paperback slides off. Within what range does the coefficient of static friction between the two books lie?

P

ave

 W

 t

P

ave  t=W 1000 W× 3600 s= 1 kW−h

Assume a non-linear spring. Calculate velocity for non- linear and linear springs for:

F=−k x−k

2

x

2 k= 10 N m k 2 = 100 N m 2 x=0.01 m x=0.1 m x=0.2 m

A. 5 N

B. 10 N

C. 15 N

D. 25 N

E. 50 N