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
:
The complete question is how much heat energy is delivered by the iron in 30 seconds.
Heat is given by IVt, Where I is the current in Amperes, V is the voltage, and t is the time in seconds,
Therefore;
Heat energy = 120 × 10 ×30
= 36000 joules or 36 kJ
Heat energy is measured in joules.
Answer:
See the answers below.
Explanation:
to solve this problem we must make a free body diagram, with the forces acting on the metal rod.
i)
The center of gravity of the rod is concentrated in half the distance, that is, from the end of the bar to the center there is 40 [cm]. This can be seen in the attached free body diagram.
We have only two equilibrium equations, a summation of forces on the Y-axis equal to zero, and a summation of moments on any point equal to zero.
For the summation of forces we will take the forces upwards as positive and the negative forces downwards.
ΣF = 0
Now we perform a sum of moments equal to zero around the point of attachment of the string with the metal bar. Let's take as a positive the moment of the force that rotates the metal bar counterclockwise.
ii) In the free body diagram we can see that the force acts at 18 [cm] of the string.
ΣM = 0
![(15*9) - (18*W) = 0\\135 = 18*W\\W = 7.5 [N]](https://tex.z-dn.net/?f=%2815%2A9%29%20-%20%2818%2AW%29%20%3D%200%5C%5C135%20%3D%2018%2AW%5C%5CW%20%3D%207.5%20%5BN%5D)
The complete sentence is:
A calorimeter directly measures changes in temperature in order to calculate specific heat.
In fact, the amount of energy acquired/released by a substance is directly proportional to its change in temperature due to the equation
where Q is the amount of energy, m is the mass of the substance, Cs is the specific heat of the substance and 
is the change in temperature. Therefore, by knowing Q, m and by measuring the change in temperature, it is possible to calculate Cs, the specific heat capacity of the substance.
Answer:
43.68 J
Explanation:
Distance moved= 7.8 m
Force = 5.6 N
Work Done= Distance moved * Force
= 7.8 *5.6
=43.68 Joules
