Scientists used to say that what we call nature, that is the whole universe, was made up of matter and force; but now-a-days they find that the atoms that make up the matter are really force, so that matter itself is only a form of force. But it will be convenient to use the word force in its usual sense of energy, and to give as illustrations of the forces of nature such great powers as light, heat, electricity, gravitation, and life. The study of the first four of these forces is called the science of Physics; and physicists have discovered a great deal about them. But we can only speak here of a few of the more obvious effects of these forces, especially as far as they have been found useful to man. Take the force of gravitation. The effect of gravitation is one of the most familiar experiences in everyday life, as we know when we fall down, and when we see anything that is thrown into the air fall back again to the earth. Yet no one knows exactly what this force is Isaac Newton, the great English mathematician, discovered the law of gravitation that is the rule by which this force always seems to work; but even he could not explain what it really is. All he could say was that it seemed to be a force of attraction that tends to draw masses of matter towards each other in a certain way, namely in direct proportion to their mass and in inverse proportion to the square of their distance. Hence the earth on which we live draws all smaller objects near it towards its centre, so that, as we say, everything tends to fall on to the earth; hence the sun draws the earth towards itself, and keeps it revolving round it. But for gravitation, all the things of the surface of the earth would be flung off, the earth itself would fall to pieces, and rush off in fragments into space. Men have always been familiar with lighting; but it is only in modern times that they have identified it with electricity, and found ways of producing it and making it useful to them, in such forms...

...IB PHYSICS HL
Lab: Centripetal Force
BACKGROUND/PURPOSE:
*In this section of your lab write-up, be sure to include all equations and
background information
-For motion along a straight line, a constant net force F acting on a body of mass m produces a constant acceleration a, related to the force through Newton's law:
F = ma
-When the same object is moving in a circle at a constant speed, the acceleration of the object is given by the following equation:
a = v2/r
-In this experiment, you will use these two equations and some simple measurements to determine the unknown mass of a rubber stopper as it rotates in a horizontal circle around a fixed center point.
PROCEDURE:
The equipment that you will use is as follows:
-Glass tube
-Rubber stopper
-String
-Hanging masses (washers)
When the glass tube is swung in a small circle above your head, the rubber stopper moves around in a horizontal circle at the end of a string. The string is threaded through the tube and fastened to some washers hanging below. The force of gravity on these washers, acting along the string, provides the centripetal force needed to keep the stopper moving in a circle.
Before taking any measurements, get a feel for the apparatus. With only one washer on the end of the string to keep the stopper from getting away, whirl the stopper over your head while holding onto the string below the tube.
The mass of the stopper...

...For other uses, see Force (disambiguation).
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See also: Forcing (disambiguation)
ForceForce examples.svg
Forces are also described as a push or pull on an object. They can be due to phenomena such as gravity, magnetism, or anything that might cause a mass to accelerate.
Common symbol(s): F, F
in SI base quantities: 1 kg·m/s2
SI unit: newton
Derivations from other quantities: F = m a
Classical mechanics
History
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In physics, a force is any influence that causes an object to undergo a certain change, either concerning its movement, direction, or geometrical construction. In other words, a force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate, or a flexible object to deform, or both. Force can also be described by intuitive concepts such as a push or a pull. A force has both magnitude and direction, making it a vector quantity. It is measured in the SI unit of newtons and represented by the symbol F.
The original form of Newton's second law states that the net force acting upon an object is equal to the rate at which its momentum changes with time.[1] If the mass of...

..."gravity" after he saw an apple
falling onto the ground in his garden.
"Gravity" is the force of attraction
exerted by the earth on an object.
The moon orbits around the earth
because of gravity too. Newton later
proposed that gravity was just a
particular case of gravitation. Every
mass in the universe attracts every
other mass. This is the main idea of
Newton's Law of Universal
Gravitation.
A portrait of Issac Newton.
Courtesy of AIP Emilio Segre Visual
Archives, W.F. Meggers Collection.
The law was published in Newton's
famous work, the Principia
("Mathematical Principles of Natural
Knowledge") in 1687. It states that every
particle in the universe exerts a force
on every other particle along the line
joining their centers. The magnitude
of the force is directly proportional
to the product of the masses of the
two particles, and inversely
proportional to the square of the
distances between them.
In mathematical terms:
By team C007571, ThinkQuest2000.
where and are the masses of the two
particles,
r is the distance between the two
masses,
F is the gravitational force between
them, and
G is the universal gravitational
constant,
.
The above equation only calculates the
gravitational force of the simplest case
between two particles. What if there are
more than two? In that case, we
calculate the resultant gravitational force
on a particle by finding the vector sum of
all the gravitational...

...LAB: Force Lab
Research Question: How does the change in mass of an object affect the force and time while the object is moving down a height of 31cm?
Hypothesis: My prediction is that the greater the mass of the toy car the larger the force of gravity, as the product of the masses of two objects increases, the force of gravity that attracts them toward each other increases. According to Newton’s law of universal gravitation, “gravity and mass are directly proportional” hence, creating a greater force of gravity and a faster speed. As well as, Newton’s second law of motion is: “Force = Mass x Acceleration” and if the mass is larger the force will be greater.
Newton’s law of universal gravitation.
Newton’s law of universal gravitation.
Variables:
IV (Independent Variable): The mass of the car (kg)
DV (Dependent Variable): The time (seconds)
CV (Control Variable): same timer , same distance travelled (1.2 m), same weighing scale, height of the ramp (31 cm), surface of ramp, the same toy car.
Materials:
* A timer set to 0.00 (seconds)
* A weighing scale
* A measuring tape (meters)
* A toy car
* 5 weights, each measuring 10 grams
* A wooden ramp
* Laboratory Jack
* Scotch tape
* Calculator (for the calculations)
* Pencil/Pen
* Paper (for results table)
Method:
1. Get into groups of three or four...

...HYDROSTATIC FORCE (EXPERIMENT 1)
INTRODUCTION
The determination of force which are exerted by liquid which are at rest on surface immersed in liquids. From the study by hydrostatic, the following principles have been established :
a) There are no shear stress present when the fluid is not in motion.
b) The pressure exerted by a fluid under hydrostatic conditions. This pressure acts perpendicular to an immersed surface.
c) Hydrostatic pressure various linearly, increasing with an increase in depth.
OBJECTIVES
1. To determine the hydrostatic thrust on a plane surface partly immersed in water.
2. To determine the position of the line of action of the thrust.
3. To compare the position determined by experiment with the theoretical position .
4. To verify the formula for calculating hydrostatic thrust.
THEORY
When the quadrant is immersed in water it is possible to analyze the forces acting on the surfaces of the quadrant as follows:
The hydrostatic force at any point on the curved surface is normal to the surface and therefore resolves through the pivot point because this is located at the origin of the radii. Hydrostatic forces on the upper and lower curved surfaces therefore have no net effect – no torque to affect the equilibrium of the assembly because all of these forces pass through the pivot.
The forces on the sides of the...

...Definition of Force
A force is a push or pull upon an object resulting from the object's interaction with another object. Whenever there is an interaction between two objects, there is a force upon each of the objects. When the interaction ceases, the two objects no longer experience the force. Forces onlyexist as a result of an interaction.
Velocity, Acceleration, Momentum, and Impulse
Velocity, in physics, is a vector quantity (it has both magnitude and direction), and is the time rate of change of position (of an object). However, quite often when you read ‘velocity’, what is meant is speed, the magnitude of the velocity vector (speed is a scalar quantity, it has only magnitude). For example: escape velocity (the minimum speed an object needs to escape from a planet, say); note that this can be easily turned into a velocity, by adding ‘in the direction radially out from the center of the planet’, and that this direction is sometimes implied (if not actually stated).
Velocity is a vector measurement of the rate and direction of motion or, in other terms, the rate and direction of the change in the position of an object. The scalar (absolute value) magnitude of the velocity vector is the speed of the motion. In calculus terms, velocity is the first derivative of position with respect to time.
The most common way to calculate the constant velocity of an object moving in a straight line is with...

...Centripetal Force Lab Activity
Analysis:
1. A) Average Percent Difference:
50g: (values expressed in newtons)
Step 1: Calculate the average value of the two variables
Average Value= Value 1+ Value 2 /2
= 0.49+ 0.61/2
= 1.1/2
= 0.55
Step 2: Calculate the difference between the two variables
Difference= Value 2- Value 1
= Fc- Fg
= 0.61- 0.49
= 0.12
Step 3: Calculate % difference
% difference= difference of the variables / average of the variables x 100
= 0.12/ 0.55 x 100
= 21.81%
100g: (values expressed in newtons)
Step 1: Calculate the average value of the two variables
Average Value= Value 1+ Value 2 /2
= 0.98+ 1.84/2
= 2.82/2
= 1.41
Step 2: Calculate the difference between the two variables
Difference= Value 2- Value 1
= Fc- Fg
= 1.84- 0.98
= 0.86
Step 3: Calculate % difference
% difference= difference of the variables / average of the variables x 100
= 0.86/ 1.41 x 100
= 60.99%
150g: (values expressed in newtons)
Step 1: Calculate the average value of the two variables
Average Value= Value 1+ Value 2 /2
= 1.47+ 2.19/2
= 3.66/2
= 1.83
Step 2: Calculate the difference between the two variables
Difference= Value 2- Value 1
= Fc- Fg
= 2.19- 1.47
= 0.72...

...________.
A. A property of matter
B. A type of force
C. The speed of an object
D. Any of the above
3. P and Q are two objects with masses 100 kg and 75 kg respectively, then ________.
A. Both will have the same inertia
B. Q will have more inertia
C. P will have more inertia
D. Both will have less inertia
4. Newton's second law of motion states that an unbalanced force that acts upon an object causes it to:
A. Accelerate
B. Not accelerate (keep the same velocity)
C. Have a velocity
D. Have a displacement
5. If two boxes are pushed with the same amount of total force, and one weighs 1kg and the other weighs 100kg, which one will accelerate faster?
A. 1 kg box.
B. 100 kg box.
C. They will accelerate at the same rate.
D. Neither will accelerate.
6. What is the force acting on an object of mass 10 kg moving with a uniform velocity of 10 m/s?
A. 100 N
B. 10 N
C. 0
D. 1 N
Section B
1. A 3kg box is being pulled with a force of 12 N (See Figure 1). The position-time graph of the box is given in Figure 2.
a. Sketch a free body diagram of the forces acting on the box. (2 marks)
b. Determine the coefficient of friction between box and surface. (3 marks)
Position
Time
F = 12 N
m = 3 kg
Figure 1...