This is a physical change because there isn’t a change in composition of the substance, sand. It is only changing the shape, not having a chemical reaction of any sort. I hope this helps!
Newton's second law states that the force is proportional to the acceleration of the system, as in this case they indicate that the body moves at constant speed, the acceleration is zero, therefore
F_applied - fr = 0
F_aplied = fr
therefore the force applied by people is equal to the friction force
Answer: We prefer a convex mirror as a rear-view mirror in vehicles because it gives a wider field of view, which allows the driver to see most of the traffic behind him. Convex mirrors always form a virtual, erect, and diminished image of the objects placed in front of it.
If the gravitational attraction is equal to their electrical repulsion, we can write the following equation:
where Fg is the gravitational attraction, that can be written as follows according Newton's Universal Law of Gravitation:
Fc, due to it is the electrical repulsion between both charged spheres, must obey Coulomb's Law (assuming we can treat both spheres as point charges), as follows:
since m₁ = m₂ = 0.0024 kg, and r₁₂ = 0.1m, G and k universal constants, and q₁ = q₂ = Q, we can replace the values in (2) and (3), so we can rewrite (1) as follows:
Since obviously the distance is the same on both sides, we can cancel them out, and solve (4) for Q² first, as follows:
Since both charges are the same, the charge on each sphere is just the square root of (5):
Q = 2.066* 10⁻¹³ C.
2)
Assuming that both spheres were electrically neutral before being charged, the negative charge removed must be equal to the positive charge on the spheres.
Now, since each electron carries an elementary charge equal to -1.6*10⁻¹⁹ C, in order to get the number of electrons removed from each sphere, we need to divide the charge removed from each sphere (the outcome of part 1) with negative sign) by the elementary charge, as follows: