Physics Sec. 2.3 Open Notes Quiz

The final velocity of an object undergoing free fall from rest is proportional to 

• 
  

   $\frac{1}{2}$   $\Delta$  x

•  $\Delta$  x

•  $\sqrt{ }$  ( $\Delta$  x)

• ( $\Delta$  x)^2

An object in free fall

• experiences an increase in speed of 9.81 m/s during each second.

• moves only downward.

• undergoes a velocity decrease of 9.81 m/s during each second.

• all of the above

The graph above shows the motion of four objects. Which of the following lines represent an object in free fall? Assume positive velocity is upward.

• I only

• II only

• I and III

• I and IV

An object in free fall

• experiences no air resistance.

• undergoes a downward acceleration.

• has an acceleration with a magnitude of 9.81 m/s2 near Earth’s surface

• all of the above

The displacement of an object undergoing free fall from rest is proportional to  

•  $\frac{1}{2}$   $\Delta$  t.

•  $\Delta$  t. 

• ( $\Delta$  t)^ 2

•  (2t)^2 . 

Questions 6–8 refer to the following demonstration. 

A red ball is dropped from rest and undergoes free fall. One second later a blue ball is dropped from rest and undergoes free fall.
The red ball’s change of velocity during the third second of the demonstration is  $\Delta$  v. What is the change of velocity of the blue ball during this time interval?  

•  $\frac{1}{2}$   $\Delta$  v

•  $\Delta$  v

•  2 $\Delta$  v

• 3 $\Delta$  v

 A red ball is dropped from rest and undergoes free fall. One second later a blue ball is dropped from rest and undergoes free fall. 

The red ball’s velocity at the end of 3.0 seconds is v3. What is the blue ball’s velocity at this moment of the demonstration?  

•  $\frac{1}{9}$   v3

•  $\frac{1}{4}$   v3 

•  $\frac{1}{2}$  v3

•  $\frac{2}{3}$   v3

A climber throws a rope with a velocity of 3.0 m/s downward to another climber 4.0 m directly below. What is the rope’s velocity when it reached the lower climber? Assume no air resistance and that a = g = 9.81 m/s2.

Describe the motion of the graph in your own words. Use complete sentences..

A red ball is dropped from rest and undergoes free fall. One second later a blue ball is dropped from rest and undergoes free fall.

The displacement of the blue ball during the time interval 3.04.0 s is equal to the displacement of the red ball in which of the following intervals of the demonstration?

• 0.0-1.0 s

• 1.0-2.0 s

• 2.0-3.0 s

• 3.0-4.0 s