Which statement is correct about the relationship between the instantaneous speed and the magnitude of the instantaneous velocity?

A) The average speed can be less than, greater than or equal to the magnitude of the average velocity.

B) The instantaneous speed is always equal to the magnitude of the instantaneous velocity.

C) The average speed is always less than or equal to the magnitude of the average velocity.

D) The instantaneous speed is always greater than or equal to the magnitude of the instantaneous velocity.

E) The average speed is always one-half the magnitude of the average velocity.

Suppose that an object is moving with a constant velocity. Make a statement concerning its acceleration.

A) The acceleration must be constantly increasing.

B) The acceleration must be constantly decreasing.

C) The acceleration must be a constant non-zero value.

D) The acceleration must be equal to zero.

E) A statement cannot be made without additional information

**EXPERT ANSWER**

**Answer :**C) only when the velocity is constant

Which statement is correct about the relationship between the instantaneous speed and the magnitude of the instantaneous velocity?

A) The average speed can be less than, greater than or equal to the magnitude of the average velocity.

B) The instantaneous speed is always equal to the magnitude of the instantaneous velocity.

C) The average speed is always less than or equal to the magnitude of the average velocity.

D) The instantaneous speed is always greater than or equal to the magnitude of the instantaneous velocity.

E) The average speed is always one-half the magnitude of the average velocity.

**Answer :**B) The instantaneous speed is always equal to the magnitude of the instantaneous velocity.

Suppose that an object is moving with a constant velocity. Make a statement concerning its acceleration.

A) The acceleration must be constantly increasing.

B) The acceleration must be constantly decreasing.

C) The acceleration must be a constant non-zero value.

D) The acceleration must be equal to zero.

E) A statement cannot be made without additional information

**Answer :**D) The acceleration must be equal to zero.