Answer:
a.)
I.) Open system
II.) Closed system
b.)
The total momentum of the object and earth system stay the same as the object fall toward the earth
The kinetic energy of the object increases as the object falls toward the earth.
Explanation:
a.)
I.) The system containing only the object is an open system because of the influence of external forces and presence of matters. External forces in this scenario means gravitational force acting on the object. And air is the matter that has influence on the object.
II.) The system containing only the object and earth is a closed system. Because in a closed system, there are no external dissipative forces acting on it. Universe is a closed system. And the mechanical energy of a close system is conserved. The mechanical energy will remain constant. In other words, it will not change (become more or less). This is called the Law of Conservation of Mechanical Energy.
b.) The total momentum of the object and earth system stay the same as the object fall toward the earth. Because momentum will always be conserved.
The kinetic energy of the object increases as the object falls toward the earth. When the object was initially at rest, kinetic energy equals zero
Answer:

Explanation:
Height of man= 6ft
Height of light=1 5ft
Let BC=x and CD=y
BD=x+y
Triangle ABD and ECD are similar
When two triangles are similar then the ratio of their corresponding sides are equal






Differentiate w.r.t t

We have 
Substitute the value then we get


Rate at which the tip of shadow is moving=
Rate at which the tip of shadow is moving=
Rate at which the tip of shadow is moving=
Answer:
pressure = force ie 500 N divided by area ie 0.05m².
p=f by a
p= 500n divided by 0.05 m²
p= 10,000 pascal
The troposphere is the lowermost layer of the Earth's atmosphere. Most of the weather phenomena, systems, convection, turbulence and clouds occur in this layer, although some may extend into the lower portion of the stratosphere.
Answer:
F = 0.112 N
Explanation:
To find the magnitude of magnetic force on the wire, you use the following formula:
(1)
L: length of the wire = 200cm = 0.2m
i: current in the wire = 30 A
B: magnitude of the magnetic field = 0.055 T
θ: angle between the directions of L and B = 20°
You replace the values of L, i, B and θ in the equation (1):

hence, the magnetic force on teh wire is 0.112N