MgCl2 is magnesium chloride.
Hope this helps!
Electrons move from the sweater to the balloon. The sweater becomes positively charged, while the balloon becomes negatively charged.
Explanation:
- Sweater is a conductive material, which means it readily gives away its electrons.
- Consequently, when you rub a balloon on Sweater, this causes the electrons to move from the Sweater to the balloon's surface.
- The rubbed part of the balloon now acquired a negative charge. Objects made of rubber, such as the balloon, are basically electrical insulators, meaning that they resist electric charges flowing through them.
- This is why only part of the balloon may have a negative charge (where the wool rubbed it) and the rest may remain neutral after electrostatic process.
Answer:

Explanation:
Assume that the distance travelled initially is d.
In order to stop the block you need some external force which is friction.
If we use the law of energy conservation:

a)
Looking at the formula you can see that the mass doesn't affect the distance travelled, as lng as the initial velocity is constant (Which indicates that the force must be higher to push the block to the same speed) therefore the distance is the same.
b) If the velocity is doubled, then the distance travelled is multiplied by 4, because the distance deppends on the square of the velocity.
The answer is <span>a) large force over a long time </span>