Answer:
B 150g
Explanation:
b 150g mass of water remains the same when it changes state
W = _|....F*dx*cos(a)........With F=force, x=distance over which force acts on object,
.......0.............................and a=angle between force and direction of travel.
Since the force is constant in this case we don't need the equation to be an integral expression, and since the force in question - the force of friction - is always precisely opposite the direction of travel (which makes (a) equal to 180 deg, and cos(a) equal to -1) the equation can be rewritted like so:
W = F*x*(-1) ............ or ............. W = -F*x
The force of friction is given by the equation: Ffriction = Fnormal*(coeff of friction)
Also, note that the total work is the sum of all 45 passes by the sandpaper. So our final equation, when Ffriction is substituted, is:
W = (-45)(Fnormal)(coeff of friction)(distance)
W = (-45)...(1.8N).........(0.92).........(0.15m)
W = ................-11.178 Joules
The answer is C. an electron in an orbit has a fixed energy.
Answer:
The number of oxygen molecules in the left container greater than the number of hydrogen molecules in the right container.
Explanation:
Given:
Molar mass of oxygen, 
Molar mass of hydrogen, 
We know ideal gas law as:
where:
P = pressure of the gas
V = volume of the gas
n= no. of moles of the gas molecules
R = universal gs constant
T = temperature of the gas
∵
where:
m = mass of gas in grams
M = molecular mass of the gas
∴Eq. (1) can be written as:
as: 
So,
Now, according to given we have T,P,R same for both the gases.
∴The molecules of oxygen are more densely packed than the molecules of hydrogen in the same volume at the same temperature and pressure. So, <em>the number of oxygen molecules in the left container greater than the number of hydrogen molecules in the right container.</em>
Answer:
b) The star is moving away from us.
Explanation:
If an object moves toward us, the light waves it emits are compressed - the wavelength of the light will be shorter, making the light bluer. On the other hand, if an object moves away from us, the light waves are stretched, making it redder. If from laboratory measurements we know that a specific hydrogen spectral line appears at the wavelength of 121.6 nanometers (nm) and the spectrum of a particular star shows the same hydrogen line appearing at the wavelength of 121.8 nm, we can conclude that the star is moving away from npos, since the wavelength related to that star is more expanded.
