Direction of displacement,velocity and acceleration in an oscillation

AI Thread Summary
In simple harmonic motion, the direction of displacement, velocity, and acceleration can be determined based on the chosen coordinate system, which is arbitrary. For example, in a vertical pendulum, one can define upward as positive and downward as negative, or vice versa, without affecting the physics. Acceleration is always directed towards the equilibrium point, while velocity depends on the position relative to that point. The key takeaway is that the assignment of positive or negative values is a matter of convention and does not impact the underlying motion. Understanding this flexibility can simplify analysis in oscillatory systems.
hikarigenzo
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Hi,good morning. I encountered a problem regarding simple harmonic motion. I have seen the graphs of displacement, velocity and acceleration in an oscillation. How to determine the Direction of displacement,velocity and acceleration in an oscillation? I really have no idea

Thanks
 
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hi hikarigenzo! :wink:
hikarigenzo said:
How to determine the Direction of displacement,velocity and acceleration in an oscillation?

i don't understand what you're asking about :confused:

can you give an example? :smile:​
 
Simple harmonic motion is defined (in one way) as the motion resulting when a force is proportional to a displacement and directed back towards the equilibrium point.
Displacement is a vector... distance from equilibrium point.
Acceleration is proportional to force (a=F/m) and is therefore directed towards the equilibrium point
Velocity... depends on position
 
Thanks for the replies, I should rephrase my question. The positive or negative sign in displacement in the oscillation depends on what? For example, a pendulum that oscillates vertically, how do we give the positive or negative? Is it based on the direction like upwards positive and downwards negative or positive is given to the position above the equilibrium? Thanks. I reply quite slow because I am now preparing for exam.
 
hi hikarigenzo! :smile:
hikarigenzo said:
… For example, a pendulum that oscillates vertically, how do we give the positive or negative? Is it based on the direction like upwards positive and downwards negative or positive is given to the position above the equilibrium?

for a pendulum, it's arbitrary …

you can make left positive, or you can make right positive, it makes no difference

for a bungee jumper, you'd make up positive, simply because making down positive would be annoying (but you could make down positive if you really wanted to)

for a spring, you'd usually make extension positive, but you don't have to, and if two springs are joined together, you often make extension positive for one and extension negative for the other

to sum up …

it's arbitrary, don't worry about it! :biggrin:​
 
tiny-tim said:
hi hikarigenzo! :smile:


for a pendulum, it's arbitrary …

you can make left positive, or you can make right positive, it makes no difference

for a bungee jumper, you'd make up positive, simply because making down positive would be annoying (but you could make down positive if you really wanted to)

for a spring, you'd usually make extension positive, but you don't have to, and if two springs are joined together, you often make extension positive for one and extension negative for the other

to sum up …

it's arbitrary, don't worry about it! :biggrin:​


Thanks. I got it
 

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