Answer:
a. Value of MA is always lesser than VR because mechanical advantage decreases due to the friction and weight of moving parts of the machine.
b.Efficiency of lever is never 100 or more because it will always lose some tiny (sometimes immeasurable) percentage of power due to the lever bending.
c.Because it helps to apply more torque.
d.Because the upright snip has the blades rotated 90° from the handles.
e.because some of the input work is used to overcome friction.
f.because the load arm is always longer than effort arm.
g.because the effort arm is always longer than load arm of these Lever.
h. because if the effort distance is greater than load distance there will be magnification of force and the metals could easily cut.
i. because the wheelbarrow's wheel and axle help the wheelbarrow to move without friction thus making it easier to push or pull.
In my opinion, the correct answer among the choices listed above is option C. The Big Bang Theory states that between 15 and 20 billion years ago, the universe began expanding out of an enormous explosion. However, the exact number is approximately 13.8 billion years ago.
Answer: True
Refraction is a phenomenon in which the light bends or changes its direction (and changes the speed of propagation, as well) <u>when passing through a medium</u> with a refractive index 
<u>different from the other medium. </u>
Where the Refractive index is a number that describes how fast light propagates through a medium or material:
Being a relation between the speed of light in vacuum 
and its speed in the other medium 
.
It is important to note that in this process, the wavelength may be modified because it depends on the medium, however, the refracted ray of light does not change its frequency.
Answer:
2. the number of seconds to perform ten oscillations.
Answer: Frictional force
Explanation:
Since the body is moving at constant velocity, this means that the acceleration of the body is zero. Frictional force is a force of opposition which tends to oppose the moving force of an object on a flat surface.
Mathematically, summation of force on the car along the road will be
Fm - Ff = ma
Fm = moving force
Ff = frictional force
m = mass of the body
a = acceleration of the body
Since a = 0, we have;
Fm -Ff = 0
Fm = Ff (which shows that the two forces acting on the body are equal and opposite)
This frictional force will tend to keep the body at equilibrium.
