ERASMUS PLUS-  ORIONS- Entry Test

   PHYSICS

1-If we observe that a body is not subject to forces accelerates, what should we conclude?

a-that the system of reference in which we are, is inertial

b-that the system of reference in which we are, is not inertial

c-that the system of reference in which we are, is  approaching the Sun

d-that the system of reference in which we are, is moving away from the Sun

 

2-If you see a balloon still in the air, it is fair to say that:

a-It does not act any force on it

b-It acts only the wind force on it that keeps it raised from the ground

c-more forces acting on it but their resultant is zero

d- It is a not a physical situation possible

 

3-A train travelling in a curve with a speed v ⃗ subjected to a centripetal force Fc. At a certain point, it reduces to 1/3 its speed. What is the new value of the centripetal force?

a-Fc / 3

b-3fc

c-9Fc

d-Fc / 9

 

4-Two metal balls of different weight  are moving on a horizontal plane towards each other,  with different speed. Neglecting any external force and assuming their elastic collision, which of the following statements is correct?

 

a- in the collision the total kinetic energy and the total momentum are conserved

b--in the collision the total kinetic energy is conserved, but not the total momentum

c-it is conserved in the collision the total momentum, but part of the kinetic energy is dissipated

d-the impact modification is both  on the total kinetic energy and in the total momentum

 

5-The angular momentum of the Earth  calculated and compared  to the center of the Sun is:

a-  Greater to  aphelion than at perihelion

b-Lower to aphelion than at perihelion

c-constant all along the orbit

d-equal aphelion and perihelion, but changes in all other points of the orbit

 

6-The period of a satellite on a circular orbit is:

a-directly proportional to the square root of the cube of the radius of the orbit

b-inversely proportional to the square root of the cube of the radius of the orbit

c-directly proportional to the cube root of the square of the radius of the orbit

d-inversely proportional to the cube root of the square of the radius of the orbit

 

7-The radiation heat is transmitted through

a-photons

b-electromagnetic waves

c-by contact between the bodies that are at different temperatures

d- solar waves