 Introduction to Circular Motion
 Physics 

HomeNewton's LawsMomentum & ImpulseProjectile Motion & Mechanical EnergyCircular MotionLinks & Extras IntroductionIn uniform circular motion the magnitude of the velocity of the object in motion remains constant. For example at car turning around a circular curve will stay at 12 m/s throughout the entire turn (provided the driver does not brake). The direction of the velocity vector is changing. A force is required in uniform circular motion.Centripetal Force & AccelerationSince an object in motion will travel in a straight line (Newton's First Law) an force must be required to accelerate the mass . This force does not cause a change in velocity as stated in the introduction, but rather it is responsible for the change in direction. The centripetal acceleration (ac) is equal to the square of the velocity (v) over the radius of the circular motion. According to Newton's Second Law, then the centripetal force (Fc) should be the mass of the object (m) times the centripetal acceleration. The equations are pictured above.Important Facts * "Centrifugal" force is a fictitious force. It is a perceived force. There is no reactive force as per Newton's Third Law. This the 'force' that you feel when you take a turn in a car or on a roller coaster. If this was a real force, then when your car slips on ice or the roller coaster your on breaks, you should fly outward perpendicular to the direction of your motion. Obviously this is not true. * If the centripetal force is removed, the object will continue on a path tangent to the circle. In other words, you should continue in a straight line in the same direction at the motion at the exact instant the centripetal force is removed. * The centripetal force vector always points to the center of the circlar motion. * The centripetal could be the tension in a string, gravity (for simple planetary orbit like in simulation), friction (i.e. the car...
...Mechanics Practical Number 2
CentrifugalForce Apparatus HFC21
Objective:
The object of the experiment is to verify that the centrifugalforce varies in direct proportion to 1. The mass of the rotating body M (Experiment parts 1 and 2) 2. The square of the speed of rotation ω (Experiment part 3) 3. The radius of gyration k (Experiment part 4) In accordance with the formula; F = Mω2k
Apparatus: CentrifugalForce Apparatus HFC21, Cast iron calibrated weights arranged as in Figs.1 and 2.
Figure 1 CentrifugalForce Apparatus HFC21
Figure 2 CentrifugalForce HFC21 detail
Theory:
According to Newton's first law of motion, a moving body travels along a straight path with constant speed (i.e., has constant velocity) unless it is acted on by an outside force. For circular motion to occur there must be a constant force acting on a body, pushing it toward the center of the circular path. This force is the centripetal (“centerseeking”) force. For a planet orbiting the sun, the force is gravitational; for an object twirled on a string, the force is mechanical; for an electron orbiting an atom, it is electrical. The magnitude F of the centripetal force is equal to the mass m of the body times its velocity squared v 2...
...Chapter 4 Newton’s Laws
Conceptual Problems
1 • While on a very smooth level transcontinental plane flight, your coffee cup sits motionless on your tray. Are there forces acting on the cup? If so, how do they differ from the forces that would be acting on the cup if it sat on your kitchen table at home? Determine the Concept Yes, there are forces acting on it. They are the normal force of the table and the gravitational pull of Earth (weight). Because the cup is not accelerating relative to the ground, the forces are the same as those that would act on it if it was sitting on your table at home. 2 • You are passing another car on a r highway and determine that, relative to you, the car you pass has an acceleration a to the west. However, the driver of the other car is maintaining a constant speed and direction relative to the road. Is the reference frame of your car an inertial one? If not, in which direction (east or west) is your car accelerating relative to the other car? Determine the Concept No. You are in a noninertial frame that is accelerating to the east, opposite the other car’s apparent acceleration. 3 • [SSM] You are riding in a limousine that has opaque windows that do not allow you to see outside. The car is on a flat horizontal plane, so the car can accelerate by speeding up, slowing down, or turning. Equipped with just a small heavy object on the end of a string, how can you use it to...
...Force & Motion
Isaac Newton – English physicist & mathematician.
Newton’s First Law of Motion(Law of Inertia):
An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalance force.
An object at rest tends to remain at rest. An object in motion tends to move at a constant speed in a straight line unless acted upon by an unbalanced externalforce.
Newton’s Second Law of Motion(Law of Acceleration):
An object’s acceleration is directly proportional to the net force acting on it and is inversely proportional to the object’s mass.
Newton’s Third Law of Motion(Law of Interaction):
For every action, there is always an equal and opposite reaction.
Force is any interaction which tends to change the motion of an object. It can also be described by intuitive concepts such as a push or pull.
Unbalanced Forces
An object is said to be acted upon by an unbalanced force only when there is an individual force that is not being balanced by a force of equal magnitude and in the opposite direction.
Direct proportion means that when one factor increases, the other factor also increases and vice versa.
Inverse proportion means that when one factor increases, the other factor decreases.
Acceleration increase in the rate or speed of something....
...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...
...Force vs. Area
Connor Blackmon
Chemistry I H, 1st Period
Mrs. Kris Clements
October 18, 2012
Problem
Will a balloon pop if it is places on a bed of nails and pressure is applied?
Hypothesis
If a balloon is placed on a bed of nails and a force is applied, then the balloon will burst.
Variables
Independent variable Force applied to the balloon and number of nails
Dependent variable Does the balloon burst?
Materials
14 inch by 14 in by .75 in plywood board x2
196 nails
4 rods (14 inches tall)
Ruler
Pen
Drill
10 latex and 10 rubber balloons
Weights (1 lb, 5 lbs, 10 lbs; multiple of each weight)
Procedures:
Assembling the Board:
Using a pen and ruler, every one inch make a mark on one of the boards, these marks should be parallel to each other
use a drill to place a nail at each one of the points made on the board, all nails will be used
On the four corners drill a hole for a 14 inch rod facing the same way as the nails
Using the drill again, make four holes in the corners of the other plywood board for the rods to slide through
Experiment Procedures:
Inflate the rubber balloons to 11 inches in diameter, all balloons should be plus or minus .2 of an inch in diameter
Place rubber balloon on the middle of the bed of nails
Slide plywood board trough the rods to sandwich to balloon
Record if the balloon pops or not and weight applied to balloon...
...Physics notes
Force is an agent which produces or tends to produce motion in an object, stops or tends to stop , motion of an object
Newton's 1st law of motion:
If an object is at rest, will remain at rest until or unless an external force act on it. If an object is in motion , it continues its motion until or unless an external force act on it
Newton's 1st law of motion is also called first law of inertia.
Inertia:
The tendency of an object to resist any change in its state of motion or rest is called inertia.
Inertia is the measure of mass in an object.
Heavier object are difficult to bring in motion or in rest because they've greater inertia.
Newton's 2nd law of motion:
Force produces acceleration in an object in its own direction. The acceleration is directly proportional to the force and inversely proportional of the mass of the object.
Resultant force is unbalanced force.
F=ma , where F is the resultant force.
Q: the mass of a boy n his bicycle is 30kg, wants to accelerate at 1.5per sec square if the opposing force is acting on both is 40N
Find the force needed for this acceleration.
Q2: a car of weight 50,000N is moving with a uniform speed of 20meters per sec
The opposing force is acting on the car is 600N
Find:
a: the force applied by the engine
b: if the engine...
...* Constant speed = no acceleration = sum of all net forces is zero
* An object in orbit around the earth is not truly weightless
* Sitting half as far away from your class mate the gravitation force is four times as strong. (re2)
* Newton’s First Law inertia an object that is not moving will remain at rest (ex: and apple hanging from a tree)
* The reason you head feels like it jerks back ward is when pulling away from a stop sign is due to Newtons first law
* If two forces that are identical in strength but exactly opposite in direction act on the same object that object will not necessarily be motionless
* When drawing a FBD, the net force must not be included
* 2 people pushing an object across a frictionless surface will result in twice the acceleration than if only one was pushing. Assume the object slides in both cases and both people push with same force (true)
*
Types of forces:
* Dynamics: the study of motion
* No movement forces are balanced
* Applied Force: a force that results when one object makes contact with another (pushes or pulls it)
* Tension: a pulling force, with a rope/ string
* Normal force: only when in contact with something ie. The ground. Points away from surface
* Friction: opposes the sliding of two surfaces cross one...
...Force in effect when car brakes
A car of mass m=1200 kg is traveling at a speed of 50km/h. Suddenly the brakes are applied and the car is brought to a stop over a distance of 20m. Assuming constant breaking force find:
(1) the magnitude of the breaking force,
(2) the time required to stop.
(3) What will be the stopping distance if the initial speed is 100km/h?
Solution.
Most of problems from Dynamics can be seen as “two parts problem”, one involving kinematics and the other  dynamics. This is a consequence of Newton’s Second Law  Force is a product of mass and acceleration.
Acceleration by itself is a purely “kinematical” problem. When mass is involved, we go into Dynamics.
In our problem the following are given:
m = 1200 kg – mass of the car,
v1 = 50 km/h – initial speed in the first case,
D1 = 20m – stopping distance in the first case,
v2 = 100 km/h – initial speed in the second case.
We are suppose to find:
F = ? – magnitude of breaking force,
t = ? – the time required to stop,
D2 = ?<="" p="">
We write down formulas which involved the unknown quantities,
F = ma (1)
a = v1/t (2)
D1 = v1t –(1/2) a t2 (3)
Some explanations:
Formula (1) is simply Newton’s Second Law of Motion,
formula (2) – the speed decreases from v1 to 0 during time t. Assuming constant breaking force means constant acceleration (deceleration or acceleration...