Explanation:
The density of a solid copper is 8960kg/m^3 while the density of a molten copper is 7900kg/m^3 this is due to the difference in the state of matter, the solid copper is in solid state while the molten copper is in form of a liquid. In the solid copper atoms are tightly pack while they atom are not tightly packed.
Answer:

Explanation:
The density of an object is given by

where
m is the mass of the object
V is its volume
In this problem,
m = 42 kg
V = 22 m^3
Substituting into the equation, we find the object's density:

Answer:
I = 6 A
Explanation:
Given that,
Power of an electric heatr, P = 1.38 kW
The voltage of the mains supply, V = 230 V
We need to find the current through the heater. The electric power in terms of voltage and current is given by :

So, the current through an electric heater is 6 A.
Answer:
The Force exerted by the two objects will be same and 4,401,189.49 × 10−11 N
Explanation:
Let m1 be the mass of the first object and m2 be the mass of the second object and the distance between them be d. Then
m1= 181kg
m2= 712 kg
d= 0.442 m
G is the gravitational Constant
According to Newtons Law Gravitational Force is given by
F=G m1 m2 /d²
F= 6.672 × 10−11 ×181×712/(0.442)²
F= 859,576.24 × 10−11/0.195364
F= 4,401,189.49 × 10−11 N
The Force exerted by the two masses on the third mass will be same and 4,401,189.49 × 10−11 N