Answer:
W=1055N
Explanation:
In order to solve this problem, we must first do a drawing of the situation so we can visualize theh problem better. (See attached picture)
In this problem, we will ignore the board's weight. As we can see in the free body diagram of the board, there are only three forces acting on the system and we can say the system is in vertical equilibrium, so from this we can say that:
so we can do the sum now:
when solving for the Weight W, we get:
and now we can substitute the given data, so we get:
W=410N+645N
W=1055N
Explanation:
By the statement, Efficiency of a machine is 60% it is meant that 'The work output is 60% of the work input'. If you apply 100J of energy for a machine, it will be able to life load of 60 J only
Answer:
(a) 
(b) 
Explanation:
(a) We use Newton's law of universal gravitation, in order to calculate the gravitational force between electron and proton:
Where G is the Cavendish gravitational constant, 
and 
are the masses of the electron and the proton respectively and r is the distance between them:
The minus sing indicates that the force is repulsive. Thus, its magnitude is:
(b) We use Coulomb's law, in order to calculate the electric force between electron and proton, here k is the Coulomb constant and e is the elementary charge:
Its magnitude is:
Well a superconductor is a metal that acts strangely when cooled down to a certain temperature and a semiconductor and on the flip side a semiconductor<span>, is a material that has a conductivity somewhere between that of a conductor and an insulator. that is pretty much what i know i hope this helps</span>
