Answer:

Explanation:
We should first find the velocity and acceleration functions. The velocity function is the derivative of the position function with respect to time, and the acceleration function is the derivative of the velocity function with respect to time.

Similarly,

Now, the angle between velocity and acceleration vectors can be found.
The angle between any two vectors can be found by scalar product of them:

So,

At time t = 0, this equation becomes

Answer:
Correct sentence: gravitational potential energy of the mass on the hook.
Explanation:
The mechanical energy of a body or a physical system is the sum of its kinetic energy and potential energy. It is a scalar magnitude related to the movement of bodies and to forces of mechanical origin, such as gravitational force and elastic force, whose main exponent is Hooke's Law. Both are conservative forces. The mechanical energy associated with the movement of a body is kinetic energy, which depends on its mass and speed. On the other hand, the mechanical energy of potential origin or potential energy, has its origin in the conservative forces, comes from the work done by them and depends on their mass and position. The principle of conservation of energy relates both energies and expresses that the sum of both energies, the potential energy and the kinetic energy of a body or a physical system, remains constant. This sum is known as the mechanical energy of the body or physical system.
Therefore, the kinetic energy of the block comes from the transformation in this of the gravitational potential energy of the suspended mass as it loses height with respect to the earth, keeping the mechanical energy of the system constant.
Explanation:
It is given that,
Total weight of the piston, W = F = 70 N
Area of the piston, 
Let P is the pressure exerted on the piston by the gas. The force per unit area is called the pressure exerted pressure of the gas. Mathematically, it is given by :



We know that the atmospheric pressure is given by :

So, the pressure is given by :



Hence, this is the required solution.
Convection Current
This happens when there is a noteworthy contrast in temperature between two sections of a liquid. At the point when this temperature distinction exists, hot liquids rise and cool liquids sink, and after that streams, or developments, are made in the liquid
Answer:
Explanation:
Let's look at a mathematical representation of this. The equation for tis is just a souped up version of Newton's 2nd Law:
F - f = ma. It an object is moving at a constant speed, the acceleration of that object is 0. That changes this equation to
F = f which states that the applied Force equals the frictional force, choice a.