You pull your little sister across a flat snowy field on a sled. Your sister plus the sled have a mass of 22 kg. The rope is at
1 answer:
You might be interested in
Molecular formulas:
- CH₂O;
- C₂H₄O₂;
- C₆H₁₂O₆.
The empirical formula of a compound tells only the ratio between atoms of each element. The empirical formula CH₂O indicates that in this compound,
- for each C atom, there are
- two H atoms, and
- one O atom.
The molecular weight (molar mass) of the molecule depends on how many such sets of atoms in each molecule. The empirical formula doesn't tell anything about that number.
It's possible to <em>add</em> more of those sets of atoms to a molecular formula to increase its molar mass. For every extra set of those atoms added, the molar mass increase by the mass of that set of atoms. The mass of one mole of C atoms, two mole of H atoms, and one mole of O atoms is .
- CH₂O- 30.0 g/mol;
- C₂H₄O₂- 30.0 + 30.0 = 2 × 30.0 = 60.0 g/mol;
- C₃H₆O₃- 30.0 + 30.0 + 30.0 = 3 × 30.0 = 90.0 g/mol.
It takes one set of those atoms to achieve a molar mass of 30.0 g/mol. Hence the molecular formula CH₂O.
It takes two sets of those atoms to achieve a molar mass of 60.0 g/mol. Hence the molecular formula C₂H₄O₂.
It takes sets of those atoms to achieve a molar mass of 180.0 g/mol. Hence the molecular formula C₆H₁₂O₆.
42) The sailboat travels east with velocity 
, while the current moves south with speed 
. Since the two velocities are perpendicular to each other, he resultant velocity will be given by the Pytagorean theorem:
and the direction is in between the two original directions, therefore south-east. So, the correct answer is
D) 42 mph southeast
43) Since the light moves by uniform motion, we can calculate the distance corresponding to one light year by using the basic relationship between velocity, space and time. In fact, we know the velocity:
and the time is one year, corresponding to:
therefore, the distance corresponding to one light year is:
Therefore, the correct answer is D.
44) For the purpose of the problem, we can assume that the light travels instantaneously from the flash to us (because the distances involved are very small), so the time between the flash and the thunder corresponds to the time it took for the sound to travel to us.
The speed of sound is
And since the time between the flash and the thunder is t=3 s, the distance is
Therefore, the correct answer is A) 3/5 mile.
and the direction is in between the two original directions, therefore south-east. So, the correct answer is
D) 42 mph southeast
43) Since the light moves by uniform motion, we can calculate the distance corresponding to one light year by using the basic relationship between velocity, space and time. In fact, we know the velocity:
and the time is one year, corresponding to:
therefore, the distance corresponding to one light year is:
Therefore, the correct answer is D.
44) For the purpose of the problem, we can assume that the light travels instantaneously from the flash to us (because the distances involved are very small), so the time between the flash and the thunder corresponds to the time it took for the sound to travel to us.
The speed of sound is
And since the time between the flash and the thunder is t=3 s, the distance is
Therefore, the correct answer is A) 3/5 mile.