Distance and Displacement 7 grade

 

 

Welcome back to our Blog

The topic for today is Distance and Displacement

Let start remembering the definition of these two magnitudes

Distance is how far an object travels. Distance does not depend on direction. Distance is represented with a lower case d. Distance (d). For calculate distance we add all the sections of the travel.

Displacement is the difference between an object´s final position and its initial position. Displacement does depend on direction. In displacement we need to indicate the direction of the movement, examples of directions right-left, up-down, and N, S, E, W. Displacement is represented ΔX. For calculate displacement we use the following formula

ΔX= Xfinal –Xinitial.

We invite you to solve the following problems about distance and displacement

1.    A truck travels to and from a stone quarry that is located 2.5 km to the east.  

What is the total distance traveled by the truck? ____________________ 

What is its displacement?  _________________________________       

Explain with a diagram:  

 

 

 

2.    A whale swims due east for a distance of 6.9 km, turns around and goes due west for 1.8 km, and finally turns around again and heads 3.7 km due east. 

What is the total distance traveled by the whale?______________________ 

What is the displacement of the whale? ____________________________ 

Explain with a diagram:  

 

 

 

3.    A football coach paces back and forth along the sidelines during a close rivalry game. The diagram below shows several of the coach’s positions and various times. At each marked position, the coach makes a “U-turn” and moves in the opposite direction. In other words, the coach moves from position A to B to C to D.

What is the total distance that the coach traveled?  _________ 

What is the coach’s final displacement? _________________  

 

4.    Two runners race each other around a circular track.  The track is 500 meters long and 159 m across (the diameter of the circle).  Runner A trips at the half- way mark and doesn’t get up.  Runner B finishes the race.   

Which runner has the greater displacement?  _________________m 

Which ran the greatest distance?  ___________________________m 

Is there a difference? Explain with a diagram:     

 

5.    Two cars start at the same point and drive in a straight line for 5 km. At the end of the drive their distances are the same but their displacements are different. Explain how this could happen.  Illustrate with a diagram.  

 

6.    Calculate distance and displacement in each one of the following situations 

a.    David walks 3km north, then turns and walks 4 km south.

b.    Taja walks twelve meters from her door to the park, the returns home to her door

c.    Neva swan 3 complete laps in a 50 meter pool (1 lap is to the other side and back).