Answer:
The force of gravity after you double the mass and the distance is half of the initial force: 
Explanation:
The initial force of gravity is:

where
is the universal gravitational constant,
is the mass of the first object,
is the mass of the second object, and
is the distance between the objects.
If the mass of the second object is doubled, now we have
, and if the distance between the objects is also doubled instead of
now we have
.
So the force of gravity now is:

and we know that 
so the new force of gravity is:

The force of gravity after you double the mass and the distance is half of the initial force.
Answer:
1) The strength of the electromagnet increases → Place a magnetic core inside the coil of wire
2) The electromagnet turns off → Turn off the battery supply
3) The poles of the electromagnet reverse → Change the direction in which the current flows
Explanation:
when current passes through a coil it behaves a an electromagnet.
Magnetic field strength is given by
B = μ N I
N is no of turns and
I is the current through coil
μ is permeability of the medium or core in the coil.
1). Magnetic core increase permeability μ so it will strengthen magnetic field:
B = <u>μ</u> N I
2). When the battery turns off current becomes zeroi.e I=0
So B = μ N * 0
⇒ B = 0
so electromagnet turns off
3). Direction of magnetic field can be determine by right hand rule, i.e curl the fingers in the direction of current, thumb will point in the direction of north pole.
so changing current direction will change direction of magnetic field.
Answer:
I think it is the last one.
Explanation:
I am not sure because i am stuck on this one, too.
During an exothermic reaction; light and heat are released into the environment.
An exothermic reaction is one in which heat is released to the environment. This heat can be physically observed sometimes like in an a combustion reaction.
In an exothermic reaction, the enthalpy of the reactants is greater than the enthalpy of the products.
This heat lost is sometimes felt as the hotness of the vessel in which the reaction has taken place.
In conclusion, light and heat are released into the environment in an exothermic reaction.
Learn more: brainly.com/question/4345448