# centripetal acceleration and tangential acceleration

**centripetal acceleration and tangential acceleration**in previous topic we have covered basic concepts of circular motion and its parameter involved in circular motion like angular displacement, angular velocity angular acceleration time period frequency i will suggest you before going to study this topic first you study previous post basic concept of circular motion very interesting and hidden concept elaborated in depth and easy way to understand circular motion link

**hidden concepts circular motion**today we will discuss acceleration in circular motion that is called

**centripetal acceleration**today you will learn there is no only centripetal acceleration in circular motion there are four acceleration in circular motion we will study here all types of acceleration involved in circular motion so far we have studies

**centripetal acceleration**(a๐ธ)

**centripetal acceleration**comes in picture due to change in direction of velocity very important point since centripetal acceleration is a vector quantity hence its direction is always towards the center of circle along the radius as shown in above figure where its value is a๐ธ = vยฒ/r where v is speed and r is radius now from previous post we have study v = r๐ for circular motion only see the first post where we can’t write v = r๐ so put value of in above equation we can also get a๐ธ = rยฒ๐ยฒ/r = r๐ยฒ so we can also write a๐ธ =r๐ยฒ where ๐ is angular velocity now i hope you have got how centripetal acceleration comes in picture now its formula derivation we discuss in next post don’t worry.

**Tangential acceleration**(a๐)

this** **acceleration arises due to change in speed of particle or change in magnitude of velocity hence if particle velocity magnitude is changing due to this a acceleration will come in picture which is called tangential acceleration this is also a vector quantity hence its will have definitely direction now direction depend upon the velocity magnitude if velocity magnitude is increasing then direction will be along the velocity direction and if velocity is decreasing then direction will be opposite to velocity direction tangent to the radius as shown in above picture now its value is define as a๐ = d|v|/dt remember this is change in speed upon change in time concept it is not change in velocity upon change time v = velocity and | v | = speed hence in tangential acceleration has a condition if velocity is constant then d|v|/dt = 0 because constant differentiation is zero so in this case a๐ = d|v|/dt =0 so only centripetal acceleration will be there no tangential acceleration sometime centripetal acceleration is also called normal acceleration or perpendicular acceleration because it is perpendicular to the surface and tangential acceleration is called parallel acceleration because it is parallel to surface as shown above figure .**Net acceleration(**a๐ท๐ฎ๐ฝ)** **this is due to total change in velocity due to direction and velocity magnitude both it is called net acceleration now its value is ** ** a๐ท๐ฎ๐ฝ = |dv/dt| now its direction will not be in velocity direction because a๐ธ and a๐ are always perpendicular hence a๐ท๐ฎ๐ฝ resultant will be a๐ท๐ฎ๐ฝ = โa๐ธยฒ+a๐ยฒ now for direction use triangle law tan๐ฐ = a๐ธ/a๐ now we will see some questions to clear concepts.

Q if tangential velocity v= 2t and radius r =9m find a๐ธ,a๐ and a๐ท๐ฎ๐ฝ at t =3s.

Ans for velocity v= 2t put t=3 v =2*3 =6m/s

centripetal acceleration a๐ธ = vยฒ/r = 6*6/9 = 4m/sยฒ

tangential acceleration a๐ = d| v |/dt = 2m/sยฒ

net acceleration a๐ท๐ฎ๐ฝ = โa๐ธยฒ+a๐ยฒ = โ4ยฒ+2ยฒ = โ20

Q2 if ๐ = 2t and radius r =2 find a๐ธ,a๐ and a๐ท๐ฎ๐ฝ

now you can solve this problem yourself using v = r๐ .**Angular acceleration**(๐ )** **change in angular velocity divided by change in time ๐avg = โ๐/โt or ๐inst = d๐/dt

Q if ๐ = tยฒ +1 find ๐ in 0 to 2s and at 2s.

Ans angular acceleration in 0 to 2s put t=0 ๐0 = 1 now put t=2s ๐2 = 2*2+1 = 5 โ๐ = 5-1 = 4 hence ๐avg = โ๐/โt = 4/2 =2 rad/sยฒ

now for ๐ at 2s ๐inst = d๐/dt = 2t = 2*2 = 4 rad/sยฒ

now one relation in angular acceleration and linear acceleration

a๐ = r๐ where a๐ is tangential acceleration .

Q if | v | = constant in a circular motion then find ๐, a๐,a๐ธ which will be constant ?

Ans since | v | is constant then ๐ = v/r here both v and r constant then ๐ will be constant hence ๐ = dw/dt = 0 which is constant now for a๐ we know a๐ = r๐ = 0 which is also constant now for a๐ธ = vยฒ/r here v and r are constant then a๐ธ magnitude will be constant but a๐ธ is a vector quantity and its direction is variable all the time in circular motion hence it will not be constant it will be variable remember this is important concept this is all about today topic we will continue in next post i hope you have enjoyed learning **centripetal acceleration and tangential acceleration**** ** thanks for reading.

dated 16th sep 2018

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