Answer:
v₁ = 3.5 m/s
v₂ = 6.4 m/s
Explanation:
We have the following data:
m₁ = mass of trailing car = 400 kg
m₂ = mass of leading car = 400 kg
u₁ = initial speed of trailing car = 6.4 m/s
u₂ = initial speed of leading car = 3.5 m/s
v₁ = final speed of trailing car = ?
v₂ = final speed of leading car = ?
The final speed of the leading car is given by the following formula:

<u>v₂ = 6.4 m/s</u>
The final speed of the leading car is given by the following formula:

<u>v₁ = 3.5 m/s</u>
Answer: 
Explanation:
According to Newton's law of universal gravitation:
Where:
is the module of the force exerted between both bodies
is the universal gravitation constant.
and
are the masses of both bodies.
is the distance between both bodies
In this case we have two situations:
1) Two bags with masses
and
mutually exerting a gravitational attraction
on each other:
(1)
(2)
(3)
2) Two bags with masses
and
mutually exerting a gravitational attraction
on each other (assuming the distance between both bags is the same as situation 1):
(4)
(5)
(6)
Now, if we isolate
from (3):
(7)
Substituting
found in (7) in (6):
(8)
(9)
Simplifying, we finally get the expression for
in terms of
:
Answer:
Double the current
Explanation:
The energy delivered by the heater is related to the current by the following relation:
E= 
let R * t = k ( ∴ R and t both are constant)
so E= k 
Now let:
E2= k I₂^2
E2= 4E
⇒ k I₂^2= 4* k 
Cancel same terms on both sides.
I₂^2= 4* 
taking square-root on both sides.
√I₂^2 = √4* I^2
⇒I₂= 2I
If we double the current the energy delivered each minute be 4E.