1. Ian leaves his 3rd floor apartment to pick up lunch, but when he gets outside, he realizes that he has forgotten his car keys. His wife, Jane, realizes this and opens the window to toss his keys to him. Jane tosses the keys, which have a mass of 35 grams, with an initial speed of 3.0 m/s. By the time the keys reach Ian, gravity has done +3.5 J of work to the keys, and air resistance has done -2.1 J of work to the keys. What is the speed of the car keys when they reach Ian, just before he catches them? 2. 5. After a bicyclist travels 20 km, how many rotations have the wheels made? The radius of the bicycle wheels is 0.30 m.
3. 6. A 35 kg child slides down a 5.0 m long slide as shown. As the child slides, there is a kinetic friction force between the child and the slide with a coefficient of kinetic friction of 0.20. How much work (including the sign) did the gravitational force do to the child when the child slides from the top of the slide to the bottom?

  1.the balanced   chemical equation is as below

cu +   2 ag(no)₃ → cu(no₃)₂   +2 ag

2.the   much silver   produced   is   50.9 g

step 1: find the   moles of cu

moles =   mass÷   molar mass

  from periodic table the molar mass of cu = 63.5 g/mol

moles is therefore = 15.00 g÷ 63.5 g/mol = 0.236   moles

step 2: use the mole ratio to determine the   moles of ag

from equation above   cu: ag   is 1: 2

therefore the moles of ag   =0.236   moles   x 2/1 =0.472   moles

step 3: find the mass   of ag

mass = moles x molar mass

from periodic table   the molar mass of ag =107.87 g/mol

mass   = 0.472   moles x 107.87 g/mol = 50.9 g

3.   the   much   silver   collected worth is   1.797 oz

  convert   50.9 g   to oz

that is   1 gram = 0.0353 oz

          50.9 grams =?   oz

by cross multiplication

={(50.9 grams x 0.0353 oz) / 1   gram}   =1.797 oz

  the unit of the measure =

explanation:

  the property that is quantified by the energy needed per of material to raise the temperature by one.

  si unit of energy = joule (j)

  si unit of temperature = kelvin (k)

  si unit of mass of material = kilogram (kg)

the property that is quantified by the energy needed per of material to raise the temperature by one is called specific heat.

the unit of specific heat is