A2.5-kg box, sliding on a rough horizontal surface, has a speed of 1.2 m/s when it makes contact with a spring. the block comes to a momentary halt when the compression of the spring is 2.0 cm. the thermal energy generated by friction, from the instant the block makes contact with the spring until it comes to a momentary halt, is 0.5 j (b) what is the coefficient of kinetic friction between the box and the rough surface?

Explanation:

Given

mass of box

speed

compression in the spring

Total Initial energy

Thermal energy generated is

this thermal energy is produced by friction force

Work done by Friction Force is

where

contradicts the fact that friction is present because shows there is no friction so either surface is friction less or compression in the system should be more than 2 cm

  the grams     of oxygen gas   that can be produced     is 20.6   grams of o₂

calculation

2liclo₃ →   2 licl + 3 o₂

step 1:   find the moles of liclo₃

moles = mass÷ molar mass

from periodic table the molar mass of liclo₃ =6.9 +35.5   +(16 x3) =90.4 g/mol

moles=38.7 g÷90.4 g/mol=0.4281   moles

step 2:   use the   mole ratio   to calculate the moles of o2

from equation above, liclo₃: o₂   is 2: 3  

therefore the moles of   o₂=0.4281 moles x3/2 =0.6422   moles

step 3: find mass   of o₂

mass= moles x molar mass

from periodic table the   molar mass of   o₂ = 16 x2= 32 g/mol

mass=0.6422   moles   x   32 g/mol = 20.6 grams of o₂

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pour in room temperature or cold water. cover the pitcher and refrigerate. steep white or green tea for 6 to 8 hours; steep black or oolong tea for 8 to 12 hours.jun 28, 2015