PHY Chapter 3

A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the opposite direction has a speed of A) 0 m/s. B) 3 m/s. C) 4 m/s. D) 6 m/s

A) 0 m/s

An object covers a distance of 8 meters in the first second of travel, another 8 meters during the next second, and 8 meters again during the third second. Its acceleration is A) 0 m/s2. B) 5 m/s2. C) 8 m/s2. D) 24 m/s2.

A) 0 m/s2

A pot that falls from a ledge and hits the ground 45 m below hits the ground at A) 30 m/s. B) 60 m/s. C) 120 m/s. D) more than 120 m/s

A) 30 m/s.

Neglecting air resistance, a ball projected straight upward so it remains in the air for 10 seconds needs an initial speed of A) 50 m/s. B) 60 m/s. C) 80 m/s. D) 100 m/s. E) 110 m/s

A) 50 m/s.

The accelerations possible for a ball on an inclined plane A) range from zero to g. B) range from g to infinity. C) have no limit.

A) range from zero to g.

While an iron block near the Earth's surface is in free fall, it undergoes an increase in A) speed. B) acceleration. C) both of these D) neither of these

A) speed.

An apple falls from a tree and hits the ground 5 meters below with a speed of about A) 5 m/s. B) 10 m/s. C) 15 m/s. D) 20 m/s. E) not enough information

B) 10 m/s

If you throw a ball straight downward (in the absence of air resistance), after leaving your hand its acceleration is A) less than 10 m/s2. B) 10 m/s2. C) greater than 10 m/s2.

B) 10 m/s2

The time it takes a car to attain a speed of 30 m/s when accelerating from rest at 2 m/s2 is A) 2 s. B) 15 s. C) 30 s. D) 60 s. E) none of the above

B) 15 s.

An object at rest near the surface of a distant planet starts to fall freely. If the acceleration there is twice that of the Earth, its speed one second later would be A) 10 m/s. B) 20 m/s. C) 30 m/s. D) 40 m/s.

B) 20 m/s

If a car increases its velocity from zero to 60 m/s in 10 seconds, its acceleration is A) 3 m/s2. B) 6 m/s2. C) 60 m/s2. D) 600 m/s2.

B) 6 m/s2

If an object moves with constant acceleration, its velocity must A) be constant also. B) change by the same amount each second. C) change by varying amounts depending on its speed. D) always decrease.

B) change by the same amount each second.

Which of the following is not a vector quantity? A) velocity B) speed C) acceleration D) all are vector quantities E) none are vector quantities.

B) speed

A ball is thrown upwards and returns to the same location. Compared with its initial speed its speed when it returns is about A) half as much. B) the same. C) twice as much. D) four times as much.

B) the same.

An 80-km/h airplane caught in a 60-km/h crosswind has a resultant speed of A) 60 km/h. B) 80 km/h. C) 100 km/h. D) 141 km/h

C) 100 km/h

A humming bird flying at 4 km/h that gets caught in a 3-km/h crosswind has a resultant speed of about A) 3 km/h. B) 4 km/h. C) 5 km/h. D) more than 5 km/h.

C) 5 km/h

Katelyn runs along the aisle of a train that moves at 8 m/s. Her speed relative to the floor is 3 m/s. Her speed relative to an observer at rest on the ground is A) 5 m/s. B) 11 m/s. C) either depending on her running direction D) none of the above

C) either depending on her running direction

When you walk at an average speed of 4 m/s, in 5 s you'll cover a distance of A) 2 m. B) 10 m. C) 15 m. D) 20 m.

D) 20 m.

Neglecting air resistance, how fast must you toss a ball straight up in order for it to take 6 seconds to return to its initial level? A) 5 m/s B) 10 m/s C) 20 m/s D) 30 m/s E) more than 30 m/s

D) 30 m/s

A car's speed 3 seconds after accelerating from rest at 2 m/s2 is A) 2 m/s. B) 3 m/s. C) 4 m/s. D) 6 m/s.

D) 6 m/s.

A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the same direction has a speed of A) 0 m/s. B) 3 m/s. C) 4 m/s. D) 6 m/s.

D) 6 m/s.

At one instant an object in free fall is moving downward at 50 m/s. One second later its speed is A) 25 m/s. B) 50 m/s. C) 55 m/s. D) 60 m/s. E) 100 m/s

D) 60 m/s.

A vehicle undergoes acceleration when it A) gains speed. B) loses speed. C) changes its direction. D) all of the above

D) all of the above

A ball tossed vertically upward rises, reaches its highest point, and then falls back to its starting point. During this time the acceleration of the ball is always A) in the direction of motion. B) opposite its velocity. C) directed upward. D) directed downward. E) none of the above

D) directed downward.