Need Some Help With Displacement =)

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In summary, the question is about finding the displacement for a car's journey with three different directions and speeds. The final answer is 28km [W 28 degrees N] and to calculate this, one can draw the displacements and use trigonometry to find the angle. Alternatively, the displacements can be written as vectors and added together. The trigonometry or arctangent is only needed to find the angle, and the answer can also be calculated using the arctangent of the vertical component divided by the horizontal component.
  • #1
CanadianChick
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Need Some Help With Displacement...please =)

I'm working independently on Grade 11 Physics, and ran across a displacement question I need some help with. So here goes:

1. Jessie drove north at 45km/h for 20 min, then turned West and drove at 54km/h for 27min. Finally she drove South at 18km/h for 6.4 min. Find her displacement



2. According to my notes Displacement= the difference from final position to initial position



The final answer according to the book is 28km[W 28degrees N] but I have no idea how to get this answer. Any help would be GREATLY appreciated. Thanks!
 
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  • #2


Draw out the displacements (displacement=speed*time) and then find the distance between the final position and the initial position. Then use trigonometry to find the angle.

So, draw a line from the origin north for the distance specified, then from there the distance west and then from the end of that distance draw the distance south. Then find the distance between where the path ended and started.

You could also write the displacements as vectors and add them together.
 
  • #3


Great =) Very helpful, thanks for the quick reply.

So there's no way to calculate it without drawing the vectors, or using Trig?
 
  • #4


The trig is just to find the angle, and all you really need is the arctangent.

With vectors, take the arctangent of the vertical component divided by the horizontal component.
 
  • #5


Great =) thank for the help!
 

What is displacement?

Displacement is the measure of an object's change in position, typically measured from its starting point to its ending point.

How is displacement calculated?

Displacement is calculated by subtracting the initial position from the final position of an object. It is often represented by the symbol Δx.

What is the difference between displacement and distance?

Distance is the total length of the path traveled by an object, while displacement is the straight-line distance between the starting and ending points. Distance is a scalar quantity, while displacement is a vector quantity with both magnitude and direction.

Can displacement be negative?

Yes, displacement can be negative. This indicates that the object has moved in the opposite direction of its initial position. For example, if an object starts at 5 meters and ends at 3 meters, its displacement would be -2 meters.

How is displacement related to velocity?

Displacement and velocity are closely related, as velocity is the rate of change of displacement over time. If an object has a constant velocity, its displacement will be equal to the product of its velocity and the time interval. This relationship is represented by the equation Δx = v x t.

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