A pendulum consists of a small object called a bob hanging from a light cord of fixed length, with the top end of the cord fixed, as represented in the figure. The bob moves without friction, swinging equally high on both sides. It moves from its turning point A through point B and reaches its maximum speed at point C$.$

A pendulum is shown swinging side to side. Four positions of the pendulum are also shown.

At point A$,$ the pendulum is at its highest point in the swing on the left.

At point B$,$ the pendulum is now moving down and to the right.

At point C$,$ the pendulum is at its lowest point of the swing.

An unlabeled position of the ball is shown on the right, with the pendulum at the same height as point A$.$

$($a$)$ At what point does the bob have nonzero radial acceleration and zero tangential acceleration?

A B$$C

What is the direction of its total acceleration at this point?

updown$$leftright

$($b$)$ At what point does the bob have nonzero tangential acceleration and zero radial acceleration?

A B$$C

What is the direction of its total acceleration at this point?

to the right and downward perpendicular to the cordto the left and downward perpendicular to the cord$$to the right and upward perpendicular to the cordto the left and upward perpendicular to the cord

$($c$)$ At what point does the bob have both nonzero tangential and radial acceleration?

A B$$C

What is the direction of its total acceleration at this point?

to the right and pointing in a direction somewhere between the tangential and radial directionsto the left and always pointing in a direction along the tangential direction$$to the left and pointing in a direction somewhere between the tangential and radial directionsto the right and always pointing in a direction along the tangential direction