Answer:
Explanation:
Work is given by the equation 
where 
is force and 
is displacement.
Displacement is defined as change in position. In this case, the box moves from 5m to 20m. Its displacement is 
.
The force acting on the box is the force of gravity, given as 
.
Therefore, the total work done is:
(two significant figures).
Answer:
The correct option is 'd': The change in shape of an object.
Explanation:
Since by definition physical change is defined as a change that changes only the form of an object or substance and producing no change in the chemical composition of the substance. Physical changes are reversible in nature.
As we can see from all the options the change in the shape of the object is a reversible change as we can always remold any substance in any shape, thus it confirms to a physical change.
The change in the molecular composition of an object is a hallmark of a chemical reaction thus indicates a chemical change.
The smell change in an object is an indication of a chemical change in the object hence is not a physical change.
Answer:
The pulse speed depends on the properties of the medium and not on the amplitude or pulse length of the pulse.
Explanation:
Hope this helps.
Answer:
Angle of refraction
Explanation:
The incident ray is the ray before it reaches the surface.
The refracted ray is the ray after it reaches the surface.
n₁ is called the index of incidence.
n₂ is called the index of refraction.
θ₁ is called the angle of incidence.
θ₂ is called the angle of refraction.
They are related by Snell's law:
n₁ sin θ₁ = n₂ sin θ₂
Answer:
The ones that are after the light that went out are also out.
Explanation:
