Answer:
50 N/m
Explanation:
Elastic energy = kinetic energy
EE = KE
½ kx² = ½ mv²
½ k (4 m)² = ½ (8.0 kg) (10.0 m/s)²
k = 50 N/m
Answer:
The mass percentage of calcium nitrate is 31.23%.
Explanation:
Let the the mass of calcium nitrate be x and mass of potassium chloride be y.
Total mass of mixture = 19.12 g
x + y = 19.12 g..(1)
Mass of solvent = 149 g = 0.149 kg
Freezing point of the solution,
= -5.77 °C
Molal freezing constant of water = 1.86 °C/m =1.86 °C/(mol/kg)
The van't Hoff factor contribution by calcium nitrate is 3 and by potassium chloride is 2.So:
i = 3
i' = 2
Freezing point of water = T = 0°C
![\Delta T_f=T-T_f=0^oC-(-5.77^oC)=5.77^oC](https://tex.z-dn.net/?f=%5CDelta%20T_f%3DT-T_f%3D0%5EoC-%28-5.77%5EoC%29%3D5.77%5EoC)
![\Delta T_f=i\times K_f\times m](https://tex.z-dn.net/?f=%5CDelta%20T_f%3Di%5Ctimes%20K_f%5Ctimes%20m)
![Molality=m(mol/kg)=\frac{\text{Moles of solute}}{\text{mass of solvent in kg}}](https://tex.z-dn.net/?f=Molality%3Dm%28mol%2Fkg%29%3D%5Cfrac%7B%5Ctext%7BMoles%20of%20solute%7D%7D%7B%5Ctext%7Bmass%20of%20solvent%20in%20kg%7D%7D)
![5.77^oC=1.86 ^oC/(mol/kg)\times (\frac{ i\times x}{164 g/mol\times 0.149 kg}+\frac{i'\times y}{74.5 g/mol0.149 kg})](https://tex.z-dn.net/?f=5.77%5EoC%3D1.86%20%5EoC%2F%28mol%2Fkg%29%5Ctimes%20%28%5Cfrac%7B%20i%5Ctimes%20x%7D%7B164%20g%2Fmol%5Ctimes%200.149%20kg%7D%2B%5Cfrac%7Bi%27%5Ctimes%20y%7D%7B74.5%20g%2Fmol0.149%20kg%7D%29)
On solving we get:
....(2)
Solving equation (1)(2) for x and y:
x =5.973 g
y = 13.147 g
Mass percent of
in the mixture:
![\frac{x}{19.21 g}\times 100=\frac{5.973 g}{19.12 g}=31.23\%](https://tex.z-dn.net/?f=%5Cfrac%7Bx%7D%7B19.21%20g%7D%5Ctimes%20100%3D%5Cfrac%7B5.973%20g%7D%7B19.12%20g%7D%3D31.23%5C%25)
The mass percentage of calcium nitrate is 31.23%.
Average speed = total distance / total time.
That's 172 km / 5 hr = 34.4 km//hr
Answer:
Yes
Explanation:
Since velocity is a vector, meaning it also relies on direction, the average speed can be different from her average velocity. An example would be if a runner turned around and ran backward after running 10 meters and returned to her starting point. If you took her average velocity of the entire trip it would actually be 0 but her average speed obviously would not be. This is why velocity can be negative but speed cannot.