Answer:
Electrical breakdown.
Explanation:
When two conductors are relatively close enough, and have a very large voltage between them, it can lead to a Dielectric breakdown. A dielectric breakdown occurs when an insulator is subjected to a high enough voltage, suddenly becomes an electrical conductor and electric current flows through it. The air between the conductors is the insulator that breaks down, leading to an electrical discharge arc to flow between the two conductors. This electrical breakdown can cause catastrophic failure of electrical equipment, and fire hazards.
Refractor, It's a refractor-esque telescope
Answer:
The mass of the earth, 
Explanation:
It is given that,
Time taken by the moon to orbit the earth, 
Distance between moon and the earth,
We need to find the mass of the Earth using Kepler's third law of motion as :




So, the mass of the earth is
. Hence, this is the required solution.
Answer:
The frictional force needed to overcome the cart is 4.83N
Explanation:
The frictional force can be obtained using the following formula:

where
is the coefficient of friction = 0.02
R = Normal reaction of the load =
=
= 
Now that we have the necessary parameters that we can place into the equation, we can now go ahead and make our substitutions, to get the value of F.

F = 4.83 N
Hence, the frictional force needed to overcome the cart is 4.83N