Physics Essay Example: Circulation Motion, Torque, Centripetal Force

Circulation Motion

Also referred to as circular motion in physics is defined as the movement of a particular object along a circle's circumference or the movement of an object along a circular path. Different factors can be observed such as the uniform angular rate of rotation and a constant speed, or the object can be moving at a non-uniform speed with a changing rate of speed. There are different examples that can be used to explain more about circular motion (Johnson-Glenberg). One of the most common examples is the rotation of a satellite around the earth at a constant height. Also the rotation of fan blades around a hub or the rotation of plane engine fans.

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Another good example is a car around a race track; this can vary between uniform and non-uniform rotation since the car has the ability to accelerate and decelerate depending on external factors such as the state of the car, professionalism of the driver or the weather during the track (Zhu et al.). Electrons moving perpendicularly to a uniform magnetic field is also another perfect example.

According to Newton's Law of motions, the moving object s undergo acceleration by a centripetal force in the direction of the center of the rotation which restrains the object from going in a straight line. The circular motion of an object requires a resultant force so as to keep the object moving through a circular constant speed. There are two different forms of circular motions as seen earlier, the uniform circular motion and the non-uniform circular motion(Johnson-Glenberg). The uniform circular motion is the motion of an object around a circular path at a constant speed, and the distance from the axis of rotation remains at a constant distance from the object at all-time but despite the speed being constant the velocity of the object does not remain constant but changes where velocity is a vector quantity which is affected by the speed and the direction the object is traveling.

On the other hand the non-uniform circular motion the object moves in a circular path but in varying speeds and since the speed is changing new variable is introduced which is referred to as the tangential acceleration in addition to the normal speed (Johnson-Glenberg). There are different applications of the circular motion in our current world such as a car taking flat turns. This involves the turning of a car either on a race truck or while driving the car. The car exerts an outward reaction force on the road as it takes the turn. Also it helps us to find things such as the required speed to negotiate a turn without slipping.

Torque

It is also referred to a moment of force, and it is the rotational force. It can simply be the thought of a twist to an object. It is calculated by the cross product of the position vector which is the distance vector and the force vector. The symbol that represents torque is usually the lowercase Greek letter tau. The magnitude of a rigid body's torque is determined by a number of factors such as the force applied on the body, the lever arm vector connecting the body and the point of force application and finally the angle between the force and lever arm vector or simple the angle between the two previous factors (Johnson-Glenberg). And this gives the Torques SI unit is Nm/rad.

The torque of an object can be identified as the force applied at an angle to a lever then multiplied by the distance between it and the lever fulcrum. A good example of this is a force of 3 newtons applied at 2m from the fulcrum will exert the same torque as a force of one newton applied six meters from the fulcrum (Zhu et al.). To get a different understanding of this the much distance from the fulcrum the more force is required to move the object. And the less the distance from the fulcrum the less force is required. And in relation to torque, the more torque is required as the distance from the lever fulcrum increases.

There are a number of real-world applications of torque name the seesaw and the wrench among many. The seesaw is one of the most basic playground tools in every child memories. It involves a lever and a fulcrum with two objects on both ends of the lever lifting each other up. The closer an object comes to the fulcrum the easier it becomes to lift the person while the further they move from the fulcrum the heaver it becomes to lift them and more torque is required to move the object (Seyboth). Physicist discus torque and use this, for example, to expound more on torque. There are other multiple applications for torque which require detailed explanations

Centripetal force

Centripetal force prevents objects which are moving in a straight line from moving off the straight line. It is a resultant force pushing the objects to the center, keeping an object in circular motion by continually changing the direction that an object is traveling. In a circle, objects are changing direction continuously needing a resultant force (Johnson-Glenberg). The resultant force is the centripetal force acting on the object taking into consideration the size and other forces. The action of other forces provides centripetal force; it does not exist in its own right.

Centripetal force must be present to counter centrifugal force in a moving object. Centripetal force requires the direction of acceleration is the same as the net force; as a consequence of Newton's second law of physics (Seyboth). Centripetal acceleration is calculated as the rate of change in velocity divided by the time change.

An example of a real-world application of centripetal force is the earth revolving around the sun. The earth is kept in place by centripetal force which is made possible by gravity. The centripetal force on a motorcycle taking a corner is made possible by friction.

Centrifugal force

Centripetal force pushes a mass towards the center; it can be contrasted with the centrifugal force which pushes a body away from the center. One may say that the two forces are two sides of a coin, they are equal and opposite (Pan et al.). When the centrifugal force acts on an object, it makes it move in a straight path; making the object act away from the center of rotation (also called inertial force). Centrifugal force is also considered as a fictitious force because it is not a force which is applied, but because we perceive it, hence use it as a point of reference.

Centrifugal force applies Newton's third law of physics which states that there is an equal and opposite reaction for every force applied (Johnson-Glenberg). Centrifugal velocity is calculated as the mass of an object multiplied by the tangential velocity, divided by the distance.

An example of a centrifugal force is a spinning disk, where the force that keeps the rope in place is the centrifugal force.

Angular momentum

Angular momentum quantifies the rotation of a body; which is a product of its angular velocity and inertia. It is defined as the angular version of momentum. It is the property of a system or mass to turn about a fixed point in a conserved state devoid of other forces. Unless acted by force, an object in momentum remains at a constant velocity and in motion; this happens because momentum is conserved (Giancoli). For the momentum of an object to stay the same, it has to keep moving with the same velocity. An object can transfer momentum to another object, and that is how it will stop moving. This is called transfer of momentum. When there are changes is angular momentum, the change results in a torque.

To get angular momentum, one multiplies the angular velocity and the moment of inertia. An application of angular momentum in real life is the annual revolution of the earth around the sun around its own axis; thus getting an orbital angular momentum.

Conservation of angular momentum

As long as the torque is zero, the speed of rotation is constant. Angular momentum is the velocity of the rotation of an object around its own axis. Conservation of angular momentum is one of the laws of conservation in physics. The other conservation laws include conservation of electric charge and conservation of energy (Giancoli). Linear momentum and angular momentum are conserved similarly in closed systems.

Mathematically, angular momentum is the angular velocity times the moment of inertia crossed with linear momentum. After the collision, angular momentum is conserved in all directions. However, the rotational force after the collision may become angular momentum.

In real life, we see a spinning top remains upright while turning and does not topple over because of gravity. We also see wheels of a bicycle, stay upright, and nothing tampers with the motion, and it remains upright and hard to be upset by anything.

Rotational Inertia

It is referred to in different terms such as moment of inertia, or angular mass and is defined as the tensor that determines the torque needed for a desired angular acceleration around a rotational axis. Different factors are considered during the calculation of moment of inertia which involves the body mass distribution of the object that needs to be moved, and the axis is chosen. More torque is required for large moments to change the body's rotation. As seen when an object is in a position to rotate around an axis a certain amount of torque must be applied on the object so as to facilitate the object to change its angular momentum (Horvath). Moment of inertia of the body is proportional to the torque needed to cause a precise amount of angular acceleration of an object and the moment of inertia is expressed in units of Kg m2 which is it the SI unit. The analysis shows that just like the role mass plays in linear kinetics, the similar role is played by moment of inertial in rotational kinetics and both exhibit a similar characteristic which is the body to resist change in its motion. Moment of inertia depends on two distinct factors which are how the mass of an object is distributed around an axis of rotation and also varies depending on the chosen axis. It is a ratio of the total angular momentum of an object to its angular velocity around a particular axis.

I = L/w

Where I am the moment of inertial, l angular momentum and w angular velocity. Constant angular momentum leads to a lower moment of inertia while the angular velocity increases. A good example to explain this is when a spinning skater pulls up their hands; this increases the speed of rotation of the athlete. There are a number of applications of moment of inertia such as FLYWHEEL of an automobile; flywheel is a heavy mass which is mounted on the crankshaft of most engines especially cars. Moments of inertia of the mass is extremely high hence helps in the storage of power within the engine. It is also used in shipbuilding, the chances of a ship to sink by means of rolling but can never sink due to pitching and this is due to moment of inertia, and this is because over pitching axis of the ship is huge compared to that of over rolling axis Also its applied to hollow shaft (Horvath). This helps it transmit more power as compared to the solid shaft and this is as a result of higher moment of inertial found in hollow shaft.

All the provided terminologies have been explained in relation to physics, and their application to daily life analyzed as well. It is important to address such things that we encounter on a daily basis.

Work cited

Giancoli, Douglas C. Physics: Principles with Applications. Pearson Higher Ed, 2016.

Horvath, Joan, and Rich Cameron. "Moment of Inertia." 3D Printed Science Projects Volume 2. Apress, Berkeley, CA, 2017. 83-96.

Johnson-Glenberg, Mina C., et al. "Effects of embodied learning and digital platform on the retention of physics content: Centripetal force." Frontiers in psychology 7 (2016): 1819.

Seyboth, Georg S., et al. "Collective circular motion of unicycle type vehicles with nonidentical...