# Kinematics Problem Solving - Physics Solutions

• Engineering
• ramadhankd
In summary, the conversation discusses a dynamic question about determining the value of maximum theta for a pendulum in motion. The equilibrium theta is determined to be pi/4 and the pendulum swings around this angle with a constant acceleration of a. The conversation also mentions two possible solutions for the motion, but does not provide any equations to determine it.
ramadhankd
Homework Statement
The homework statement/question is in my post.
Relevant Equations
So does the equations and attempted solutions. I just wanna ask whether or not my solution is correct, because the question has a triangle symbol on It, and It supposed to be complex. Solving It that easily gives me anxiety. Please kindly help.
Thanks.

Delta2
Seems to me you describe some equilibrium situation. What would ##\theta(t)## look like ?

 And I don't see when ##a=g## would normally ever happen (unless the wire breaks ).

It's actually a dynamic question. The question is on the top left in my post (problem 3/92). We need to find the value of maximum theta. In my opinion, this condition will be reached when the pendulum have no relative motion with the slider, thus having the same acceleration a = g. I just wonder if this condition I set for max theta is right. Also, I use polar coordinate approach to analyze the kinematics while in the end, It doesn't matter at all because I only need to project a into r and theta component of acceleration (the value of r, and other defining properties of a polar system doesn't matter). Is this right?

I should have read the small print ...

So the equilibrium ##\theta## is ##\pi/4## and the pendulum swings around that angle. Any way to describe the motion ? With the initial condition ##\theta = 0## the answer seems easy.

I think your condition for ##\theta_\text{max}## is correct - but it leads to two solutions.

For the motion description, I think that the motion is that the pendulum has the constant acceleration a when θ=θmax. As for the two solutions, what are those? I'm sorry for the late reply, I've been out this weekend.

You don't list any equations to determine the motion. 'I think' doesn't help.

## 1. How do I approach solving a kinematics problem?

When solving a kinematics problem, it is important to first identify the given information and what is being asked. Then, use the appropriate kinematic equations to solve for the unknown variable. It can also be helpful to draw a diagram and label the known values to better visualize the problem.

## 2. What are the kinematic equations?

The kinematic equations are a set of four equations that can be used to solve for an unknown variable in a kinematics problem. They are:
- v = u + at (final velocity = initial velocity + acceleration x time)
- s = ut + 1/2at^2 (displacement = initial velocity x time + 1/2 x acceleration x time squared)
- v^2 = u^2 + 2as (final velocity squared = initial velocity squared + 2 x acceleration x displacement)
- s = (u + v)/2 x t (displacement = average velocity x time)

## 3. What is the difference between average velocity and instantaneous velocity?

Average velocity is the total displacement divided by the total time taken, while instantaneous velocity is the velocity at a specific moment in time. In other words, average velocity gives an overall picture of how fast an object is moving over a period of time, while instantaneous velocity gives the exact velocity at a specific point in time.

## 4. How does acceleration affect an object's motion?

Acceleration is the rate of change of an object's velocity. If an object has a positive acceleration, its velocity is increasing and it is speeding up. If an object has a negative acceleration, its velocity is decreasing and it is slowing down. If an object has zero acceleration, its velocity is constant and it is moving at a steady speed.

## 5. Can kinematics equations be used for objects moving in a curved path?

No, kinematic equations can only be used for objects moving in a straight line. For objects moving in a curved path, the equations of motion for circular motion should be used instead.

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