please check these answers for me

Question

When an object is moving with uniform circular motion, the centripetal acceleration of the object
a. is circular
b. is perpendicular to the plane of motion
c. is zero
d. is directed toward the center of motion

D

What is the term for the net force directed toward the center of an object's circular path?
a. circular force
b. centrifugal force
c. centripetal force
d. orbital force

C

Which of the following can be a centripetal force?
a. friction
b. gravity
c. tension
d. all of the above

D

When an object is moving with uniform circular motion, the object's tangential speed
a. is circular
b. is perpendicular to the plane of motion
c. is constant
d. is directed toward the center of motion

i'm not really sure about this one..

thanks :)

Answer 1

I don't see how friction can be a centripetal force. It opposes the direction of motion. Gravity and tension both can be centripetal forces.

For the last question, the speed is constant (c). The answer "a" looks tempting, but speed does not have a shape.

Your other answers are correct.