What Do You Mean By CIRCULAR MOTION?

 

 

CIRCULAR MOTION

 

 

 

1.15. UNIFORM CIRCULAR MOTION

 

When a body travels equal distances in equal intervals of time, over a circular path, its speed is uniform. The motion of the body is said to be uniform circular motion. The direction of motion at any instant of time is along the tangent to the circular path at that instant. To understand this, let us consider motion of a body along a closed path.

 

Fig. 1.23 (a) shows the path of an athlete along a rectangular track ABCD. The athlete changes his direction of motion at the four corners A, B, C, D of the rectangular track, in every round. Fig. 1.23 (b) shows a hexagonal path where in every round, the direction of motion is changed at the six corners A, B, C, D, E and F. In Fig. 1.23 (c), the track is a regular octagon. In every round, the athlete has to change the direction of motion at eight corners A, B, C, D, E, F, G, H of the octagon ; and so on. We observe that as number of sides of track increases, athlete has to take turn more and more number of times. If we go on increasing the number of sides of the track indefinitely, we find that the shape of the track approaches the shape of a circle. The length of each side tends to be zero. Along the circle, the athlete has to change his direction of motion at each point. Therefore, the effective direction of motion is along the tangent to the circular path at that point as shown in Fig. 1.23 (d).

 

 

It should be clearly understood that in uniform circular motion, only the speed of the body is constant. But the direction of motion of the body is changing continuously. Therefore, velocity of the body in uniform circular motion is changing continuously. Hence uniform circular motion is an accelerated motion. We shall study in the next chapter that an external force is required to produce acceleration. Hence an external force is needed to move a body uniformly in a circle. This force is called centripetal force. To calculate speed of the body in uniform circular motion, suppose r= radius of circular path,

 

t = time taken by the body to go once around the circle

 

V = speed of the body in uniform circular motion

 

distance travelled by the body in one complete revolution = circumference of the circle

 

i.e.,  s=2 π r ,  where π = 22/7

As                  Speed=distance/time ,  v=2 π r / t

 

1.16. EXAMPLES OF UNIFORM CIRCULAR MOTION

 

Some of the Examples of uniform circular motion are :

 

1. A piece of stone tied to a thread and rotated in circle with a uniform speed. 

 

This is shown in Fig. 1.24. The necessary force F is provided by pull of the hand. When the stone is at A, its speed is along the tangent AX to the circle at A. It is towards east. Similarly, when the stone is at B, its speed is along the tangent BY to the circle at B. It is towards south as shown in Fig. 1.24. If the thread were to break at A, the stone would fly along AX.

 

 

Similarly, if the thread were to break at B, the stone would fly along BY. It means the stone continues to move along the direction it has been moving at that instant when external force ceases to act on it

 

 

2. In a sports meet, when an athlete is to throw a hammer/discuss, he holds it in hand and gives it a circular motion by rotating his body. The moment he releases the hammer/ discuss, it moves in the direction in which it was moving at the time of release.

 

3. Moon moves around the Earth uniformly in a circular orbit. The necessary force is provided by gravitational pull of Earth on the Moon.

 

4. The motion of all artificial satellites around the Earth is uniform circular motion, which is an accelerated motion. The necessary centripetal force is provided by gravitational pull of the Earth on the satellite.

 

 

5. The motion of Earth around the Sun is also uniform circular motion, which is an accelerated motion. The necessary centripetal force is provided by gravitational pull of Sun on the Earth.

 

Some basic knowledge of Computer

 

vThe word computer comes from a Greek word 'compute' which means 'to calculate'.

 

vComputer is a machine primarily designed to store and retrieve information, perform arithmetic and logical operations to produce meaningful output in desired format and therefore, it also referred as a data processor.

 

vThe salient characteristics of computers include, speed, accuracy, diligence, versatility, reliability, automation, vast storage capacity.

 

vLimitations of a computer are: not able to take decision, zero IQ, incapable to learn and implement. A computer due to its high speed of calculation, diligence, accuracy and versatility is an integrated part in all the field you can think of.

 

vReal time environment means processing of one entity is done so quickly and effectively that another entity is not affected.

 

vCache memory is a very high-speed memory which increases the speed of the CPU as it acts as buffer between the CPU and the main memory.

 

vPeripheral devices are the devices that are connected to the CPU cabinet using the USB (Universal Serial Bus) or serial ports.

 

vOperating system manages computer's hardware and software resources. It acts a link between the software and the hardware. It controls and keeps a record of the execution of all other programs that are present in the computer, including application programs and other system software.

 

vGeneral purpose application software is developed by keeping in mind the general needs of a large number of people. It can be used for a variety of tasks and is not limited to perform a particular function.

 

vThe functions of an operating system are: process management, memory management, file management, device (I/O) management, user interface.

 

vThe kernel manages the communication between the software and the hardware. Shell interacts with the user and acts as an interpreter. It translates the instructions into machine language and forwards the translated command to the Kernel to get it done.

 

vCommand Line Interface (CLI) or Character User Interface (CUI), requires text command to interact with the computer.

 

vGraphical User Interface (GUI) is the most popular and widely used interface. This interface uses icons, menus and graphics representations to display information, unlike text-based interfaces. Mobile operating system OS is especially designed to power smartphones, tablets and wearables devices.

 

vCloud computing is the delivery of computing services, such as servers, data storage, databases, networking, creating, configuring and customizing the applications online on cloud.