Answer:
1.65
Explanation:
The equation of the forces along the horizontal direction is:
(1)
where
F = 65 N is the force applied with the push
is the frictional force
m = 4 kg is the mass
is the acceleration
The force of friction can be written as 
(2), where
is the coefficient of kinetic friction
R is the normal force exerted by the floor
The equation of forces along the vertical direction is
(3)
since the bookcase is in equilibrium. Substituting (2) and (3) into (1), we find
And solving for ,
The correct answer to the question is : B) The weight of the water, and C) The height of the water.
EXPLANATION :
Before coming into any conclusion, first we have to understand potential energy of a body.
The potential energy of a body due to its position from ground is known as gravitational potential energy.
The gravitational potential energy is calculated as -
Potential energy P.E = mgh
Here, m is the mass of the body, and g is the acceleration due to gravity.
h stands for the height of the body from the ground.
We know that weight of a body is equal to the product of mass with acceleration due to gravity.
Hence, weight W = mg
Hence, potential energy is written as P.E = weight × height.
Hence, potential energy depends on the weight and height of the water.
Explanation:
Nuclear reactions are the reactions in which nucleus of an atom changes either by splitting or joining with the nucleus of another atom.
There are two types of nuclear reactions.
- Nuclear fission - In this process, large atomic nuclei splits into smaller nuclei.
- Nuclear fusion - In this process, two small nuclei combine together to form a large nuclei.
Both nuclear fission and fusion processes involve nuclei of atoms.
For example, 
Thus, we can conclude that statements which are true are as follows.
- Nuclear reactions involve the nuclei of atoms.
- The products of nuclear reactions are lighter than the reactants.
By looking at the acceleration of the object.
In fact, Netwon's second law states that the resultant of the forces acting on an object is equal to the product between the mass m of the object and its acceleration:
So, when static friction is acting on the object, if the object is still not moving we know that all the forces are balanced: in fact, since the object is stationary, its acceleration is zero, and so the resultant of the forces (left term in the formula) must be zero as well (i.e. the forces are balanced).
