The mass of an object on Earth is the same as its mass on the Moon. The weight is different.
Weight = m * g
Weight ( Moon ) = 40 kg * 1.6 m/s² = 64 N
If the mass of an object on Earth is 40 kg, its mass on the Moon is 40 kg and its weight on the Moon is 64 N.
Answer:

Explanation:
As given point p is equidistant from both the charges
It must be in the middle of both the charges
Assuming all 3 points lie on the same line
Electric Field due a charge q at a point ,distance r away

Where
- q is the charge
- r is the distance
-
is the permittivity of medium
Let electric field due to charge q be F1 and -q be F2
I is the distance of P from q and also from charge -q
⇒
F1
F2
⇒
F1+F2=
Answer:

Explanation:
We are given that
Atomic number=2
We have to find the total negative charge on the electrons in one mole of Helium.
We know that atomic number=Proton number
Proton number=Number of electrons=2
Number of electrons in Helium=2
1 mole of Helium=
atoms
We know that q=ne
Where n =Number of fundamental units
e=Charge on electron
1 e=
Using the formula

Total negative charge in 1 mole=
Hence, the total negative charge on the electrons in 1 mole of Helium=
Answer:
(a) Energy density will be equal to 
(b) Total energy will be equal to 0.0718 J
Explanation:
It is given that length of solenoid l = 78.8 cm = 0.788 m
Cross sectional area 
Number of turns of the wire N = 914
Current in the solenoid i = 8.25 A
Inductance of the wire is equal to 
(b) Total energy stored in magnetic field 
(a) Energy density will be equal to

The anwser is C it can also be A but C would make the most sense