If the acceleration of an object is always directed perpendicular to its velocity, then

A) the object is speeding up.

B) the object is slowing down.

C) the object is moving with a constant velocity.

D) the object is turning.

E) this situation would not be physically possible.

You are trying to cross a river that flows due south with a strong current. You start out in your motorboat on the east bank desiring to reach the west bank directly west from your starting point. You should head your motorboat

A) due west.

B) due north.

C) due south.

D) in a southwesterly direction.

E) in a northwesterly direction.

For general projectile motion, the horizontal component of a projectile’s velocity

A) is zero.

B) remains a non-zero constant.

C) continuously increases.

D) continuously decreases.

E) any of the above, depending on position.

For general projectile motion, the horizontal component of a projectile’s acceleration

A) is zero.

B) remains a non-zero constant.

C) continuously increases.

D) continuously decreases.

E) any of the above, depending on position.

**EXPERT ANSWER**

If the acceleration of an object is always directed perpendicular to its velocity, then

A) the object is speeding up.

B) the object is slowing down.

C) the object is moving with a constant velocity.

D) the object is turning.

E) this situation would not be physically possible.

**Answer :**D) the object is turning.

You are trying to cross a river that flows due south with a strong current. You start out in your motorboat on the east bank desiring to reach the west bank directly west from your starting point. You should head your motorboat

A) due west.

B) due north.

C) due south.

D) in a southwesterly direction.

E) in a northwesterly direction.

**Answer :**E) in a northwesterly direction.

For general projectile motion, the horizontal component of a projectile’s velocity

A) is zero.

B) remains a non-zero constant.

C) continuously increases.

D) continuously decreases.

E) any of the above, depending on position.

**Answer :**B) remains a non-zero constant.

For general projectile motion, the horizontal component of a projectile’s acceleration

A) is zero.

B) remains a non-zero constant.

C) continuously increases.

D) continuously decreases.

E) any of the above, depending on position.

**Answer : **A) is zero.