On that list of choices, 'C' is the only "example" of a plane.
None of the choices "describes" a plane.
Answer:
1) joule
2) 
3) 
Explanation:
1) Luminosity is the <u>amount of light emitted</u> (measured in Joule) by an object in a unit of<u> time</u> (measured in seconds). Hence in SI units luminosity is expressed as joules per second (
), which is equal to Watts (
).
This amount of light emitted is also called radiated electromagnetic power, and when this is measured in relation with time, the result is also called radiant power emitted by a light-emitting object.
Therefore, if we want to calculate luminosity the Joule as a unit will be used.
2) Work is expressed as force 
multiplied by the distane 
:
Where force has units of 
and distance units of 
.
If we input the units we will have:
This is 1Joule (
) in the SI system, which is also equal to 
3) The formula to calculate the percent error is:
Where:
is the experimental value
is the accepted value
This is the percent error
In a closed system, the loss of momentum of one object is same as________ the gain in momentum of another object
according to law of conservation of momentum, total momentum before and after collision in a closed system in absence of any net external force, remains conserved . that is
total momentum before collision = total momentum after collision
P₁ + P₂ = P'₁ + P'₂
where P₁ and P₂ are momentum before collision for object 1 and object 2 respectively.
P'₁ - P₁ = - (P'₂ - P₂)
so clearly gain in momentum of one object is same as the loss of momentum of other object
