Answered

Consider an object on a rotating disk a distance r from its center, held in place on the disk by static friction. Which of the following statements is not true concerning this object:

A) If the angular speed is constant, the object must have constant tangenial speed.
B) If the angular speed is constant, the object is not accelerated
C) The object has a tangenial acceleration only if the disk has an angular acceleration.
D) If the disk has an angular acceleration, the object hasboth a centripetal and a tangenial acceleration
E) The object always has a centripetal acceleration exceptwhen the angular speed is zero

Answer :

MechEngineer

Answer:

A) False

B) False

C) True

D) True

E) True

Explanation:

A) The formula for tangential speed v in term of angular speed ω and radius of rotation r is

[tex]v = \omega r[/tex]

So if the angular speed is constant and 0, the tangential speed is also 0. A) is false

B) False because of the centripetal acceleration:

[tex]a_c = \omega^2 r[/tex]

C) True because of the formula for tangential acceleration in term of angular acceleration α is

[tex]a_t = \alpha r[/tex]

D) True because same as D), if it has angular acceleration, it would have a tangential acceleration. Also from B) the centripetal acceleration will come with time as soon as angular speed is generated by angular acceleration.

E) True and same explanation as from B)

Other Questions