Rotational Mechanics Homework: Equations & Solution for Part 1 Work

Part 1 Work" In summary, the conversation discusses the calculation of total energy (E) using the equations for kinetic energy (T) and potential energy (U) as well as the use of polar coordinates. The FBDs for a mass on a table and a hanging mass are also discussed. The solution involves calculating the acceleration and velocity for each scenario.
  • #1
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Homework Statement


upload_2018-10-28_8-22-37.png


Homework Equations


E=T+U
T=1/2 mv^2
U=∫F⋅dr

The Attempt at a Solution



Part 1 Work
x=x-dot
y=y-dot
z= z-dot
r=r-dot
θ=θ-dot
[/B]
T= 0.5m(x^2 +y^2) 0.5M(z)^2
Changing to polar coordinates
T=0.5m(r^2 +rθ^2) 0.5M(z)^2

U=-Mgz

E=T+U
=0.5m(r^2 +rθ^2) 0.5M(z)^2-Mgz

z=L-r

= 0.5m(r^2 +rθ^2) 0.5M(z)^2-Mg(l-r)


I drew the FBD for both:
for mass on table
upload_2018-10-28_8-34-28.png

Fx
Fc-T=ma

Fc= mrw^2
T=Mg
mrw^2-Mg=ma

a=
rw^2-(Mg)/m
v=rw^2-(Mg)r/m

for hanging mass
upload_2018-10-28_8-44-39.png


Fc-Fg=0
Fc=Fg
Fc=Mg

No accleration or velocity

Is this the right track
 

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Please label your solution(s) with the number(s) of the part(s) that you are solving,
 
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1. What is rotational motion?

Rotational motion refers to the movement of an object in a circular or curved path around a fixed point, also known as the axis of rotation. It is a type of motion that involves both translation (movement in a straight line) and rotation.

2. How is rotational motion different from linear motion?

Rotational motion involves movement around a fixed point, while linear motion involves movement in a straight line. In rotational motion, the distance traveled is measured in terms of an angle, such as degrees or radians, rather than a linear distance.

3. What is torque?

Torque is a measure of the force that causes an object to rotate around an axis. It is calculated by multiplying the force applied to an object by the distance from the axis of rotation to the point where the force is applied.

4. How do you calculate the moment of inertia?

The moment of inertia is a measure of an object's resistance to rotational motion. It is calculated by multiplying the mass of an object by the square of its distance from the axis of rotation.

5. What is the relationship between torque and angular acceleration?

According to Newton's Second Law, the net torque acting on an object is equal to its moment of inertia multiplied by its angular acceleration. This means that a greater torque will result in a greater angular acceleration, and vice versa.

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