Answer:
Dark matter does not affect our view, humans can see through them.
Explanation:
They do not affect our view because we can see right through the (weakly interacting) dark matter, as they do not interact or interfere with electromagnetic force.
Dark matter are often invisible substances and are difficult to spot because they don't absorb or reflect light.
Answer:
The average speed can be calculated as the quotient between the distance travelled and the time needed to travel that distance.
To go to the school, he travels 2.4 km in 0.6 hours, then here the average speed is:
s = (2.4km)/(0.6 hours) = 4 km/h
To return to his home, he travels 2.4km again, this time in only 0.4 hours, then here the average speed is:
s' = (2.4 km)/(0.4 hours) = 6 km/h.
Now, if we want the total average speed (of going and returning) we have that the total distance traveled is two times the distance between his home and school, and the total time is 0.6 hours plus 0.4 hours, then the average speed is:
S = (2*2.4 km)/(0.6 hours + 0.4 hours)
S = (4.8km)/(1 h) = 4.8 km/h
Answer:
C. Evaporating water from the container.
Explanation:
The concentration of solution changes when solvent or solute are added/removed from a solution.
Answer:
the answer is B
Explanation:
speed is the rate at which the distance covered changes or the distance divided by the time taken.
scalar is always positive.
Answer:
Density is defined as:
Density = Mass/Volume
Now, density is an intensive property, this means that if you have 10 grams of a given material or 1000 grams of the same material, in both cases you will find the same density.
Then a roll of 50 pennies has the same density that a single penny.
The measures of a single penny are:
Mass = 2.5 g
Thickness = 1.52 mm
Radius = 9.525 mm
The coin is a cylinder, and the volume of a cylinder is:
V = pi*r^2*h
where:
pi = 3.14
r = radius = 9.525mm
h = thikness = 1.52mm
The volume is:
V = 3.14*(9.525mm)^2*1.52mm = 433.015 mm^3
The density will be:
D = 2.5g/433.015mm^3 = 0.00577 g/mm^3
