What is its centripetal acceleration?

[mandy9008]

Homework Statement

(a) What is the tangential acceleration of a bug on the rim of a 8.0 in. diameter disk if the disk moves from rest to an angular speed of 77 rev/min in 3.0 s? (b) When the disk is at its final speed, what is the tangential velocity of the bug? (c) One second after the bug starts from rest, what is its tangential acceleration? What is its centripetal acceleration?

Homework Equations

a_c= v_T² / R

The Attempt at a Solution

I got all of the answers in italics, I just can;t figure out the bold part.
answers in italics:
a. a=0.273 m/s²
b. v_T=0.819 m/s
c. a=0.273 m/s²
d. a_c = 0.819 m/s ² / 0.1016
a_c = 6.60 m/s²

 

[Doc Al]

d. a_c = 0.819 m/s ² / 0.1016
a_c = 6.60 m/s²

It's not clear to me what you did here. How do you calculate the centripetal acceleration? Hint: What's the speed of the bug at the point in question?

 

[mandy9008]

i used the equation: a_c= v_T² / R

 

[Doc Al]

i used the equation: a_c= v_T² / R

OK, good. What's the speed of the bug after one second? (Note that this is not the final speed you calculated in part b.)

 

[inky]

Homework Statement

(a) What is the tangential acceleration of a bug on the rim of a 8.0 in. diameter disk if the disk moves from rest to an angular speed of 77 rev/min in 3.0 s? (b) When the disk is at its final speed, what is the tangential velocity of the bug? (c) One second after the bug starts from rest, what is its tangential acceleration? What is its centripetal acceleration?

(a) Problem ask the tangential acceleration. Not centrapetal acceleration.
Find first angular acceleration (alpha). Unit!
Then find tangential acceleration a_T

 

[Doc Al]

(a) Problem ask the tangential acceleration. Not centrapetal acceleration.
Find first angular acceleration (alpha). Unit!
Then find tangential acceleration a_T

Part (a) was done correctly; she's asking about part (d), which does ask for centripetal acceleration.