Pendulum measuring acceleration of car

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SUMMARY

The discussion clarifies the correct approach to calculating the acceleration of a train using a pendulum. The acceleration is determined using the tangent function, specifically the formula atrain = g * tan(θ), where g represents gravitational acceleration and θ is the angle of the pendulum from the vertical. The vector triangle formed by the gravitational force and the train's acceleration is essential for understanding the relationship between these forces. Misconceptions regarding the use of sine versus tangent in this context were addressed and corrected.

PREREQUISITES
  • Understanding of basic physics concepts, particularly forces and vectors
  • Familiarity with trigonometric functions, specifically sine and tangent
  • Knowledge of gravitational acceleration (g) and its implications in physics
  • Ability to analyze vector triangles in physics problems
NEXT STEPS
  • Study the principles of vector addition in physics
  • Learn about the applications of trigonometric functions in physics problems
  • Explore the concept of pendulum motion and its dynamics
  • Investigate the effects of acceleration on pendulum behavior in non-inertial frames
USEFUL FOR

Physics students, educators, and anyone interested in understanding the dynamics of pendulum motion in accelerating frames, particularly in relation to trigonometric applications in physics.

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This was originally posted in a non-homework forum and does not use the template.
I came across this problem which says" A pendulum is hung by roof of a train having mass 1 kg . The train then accelerates and pendulum makes an angle with vertical. What is acceleration of train? " Is it equal to gsinθ?
 
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See, you're understanding vectors, and which components mean what.
 
Bystander said:
See, you're understanding vectors, and which components mean what.
So was I right. I searched for it over internet which says about using tan instead of sin but it seemed unreasonable to me
Thank you.
 
shayan haider said:
using tan instead of sin
My bad. What you found about tan is correct. The gravitational force is perpendicular to the train's acceleration. The force acting on the pendulum mass is the vector sum of the gravitational force and the train's acceleration.
Mea culpa.
 
Bystander said:
My bad. What you found about tan is correct. The gravitational force is perpendicular to the train's acceleration. The force acting on the pendulum mass is the vector sum of the gravitational force and the train's acceleration.
Mea culpa.
What did you mean by that. I want to learn which is correct gsintheta or gtantheta.
 
shayan haider said:
gtantheta.
The vector triangle to be examined has three sides: 1) the hypotenuse, which is the resultant of gravitational force on the pendulum, and the train's acceleration (pulling the mass toward rear of train); 2) the vertical leg, which is mg of the pendulum; and 3) the horizontal leg, which is atrainm. The relationship between the two legs of the triangle is "opposite" (horizontal) over "adjacent" (vertical), or tangent, since the angle of the resultant is measured from the vertical.
 
Bystander said:
The vector triangle to be examined has three sides: 1) the hypotenuse, which is the resultant of gravitational force on the pendulum, and the train's acceleration (pulling the mass toward rear of train); 2) the vertical leg, which is mg of the pendulum; and 3) the horizontal leg, which is atrainm. The relationship between the two legs of the triangle is "opposite" (horizontal) over "adjacent" (vertical), or tangent, since the angle of the resultant is measured from the vertical.
Oh sorry, I have got your point. You are right. Thanks for correction.
 
Bystander said:
The vector triangle to be examined has three sides: 1) the hypotenuse, which is the resultant of gravitational force on the pendulum, and the train's acceleration (pulling the mass toward rear of train); 2) the vertical leg, which is mg of the pendulum; and 3) the horizontal leg, which is atrainm. The relationship between the two legs of the triangle is "opposite" (horizontal) over "adjacent" (vertical), or tangent, since the angle of the resultant is measured from the vertical.
I mistook that first. g is not the resultant. It is component.
 
shayan haider said:
I mistook that first. g is not the resultant. It is component.
You and me both, but it's straightened out now.
 
  • #10
Please use the template
 

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