Velocity & Energy Homework: Find Speed at Low/High Points

  • Thread starter Thread starter TS656577
  • Start date Start date
  • Tags Tags
    Energy Velocity
Click For Summary
SUMMARY

The discussion focuses on calculating the speed of a ball attached to a string as it swings from a horizontal position to its lowest and highest points. The key equations utilized are the kinetic energy equation (K = 1/2mv²) and the gravitational potential energy equation (U = mgh), with the total mechanical energy conserved. The user initially calculated the speed at the lowest point to be 50.28 m/s using the formula derived from energy conservation, but this result was flagged as incorrect by an online program, indicating a need for further analysis or correction in the application of energy principles.

PREREQUISITES
  • Understanding of basic physics concepts such as kinetic and potential energy
  • Familiarity with the conservation of energy principle
  • Ability to manipulate algebraic equations
  • Knowledge of gravitational acceleration (g = 9.8 m/s²)
NEXT STEPS
  • Review the conservation of energy principles in mechanical systems
  • Investigate the effects of constraints on motion, such as the peg in this scenario
  • Explore the concept of angular velocity and its relationship to linear speed
  • Practice similar problems involving pendulum motion and energy transformations
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and energy conservation, as well as educators seeking to clarify concepts related to pendulum motion and energy transformations.

TS656577
Messages
62
Reaction score
0

Homework Statement


The string in Fig. 8-37 is L = 129 cm long, has a ball attached to one end, and is fixed at its other end. The distance d from the fixed end to a fixed peg at point P is 78 cm. When the initially stationary ball is released with the string horizontal as shown, it will swing along the dashed arc. What is its speed when it reaches (a) its lowest point and (b) its highest point after the string catches on the peg?

Homework Equations


K=1/2mv^2
U=mgh where in this case, h=L

The Attempt at a Solution


I know I need to use the conservation of energy (U(i) + K(i) = U(f) + K(f)) and then K(i)=0 and U(f)=0. So then you can use the equation mgL = 1/2mv^2 and the m's cancel out so youre left with gL = 1/2v^2. I took this to mean that I would have 9.8(129) = 1/2v^2. Solving for v, I got 50.28 m/s. The online program says that's wrong so I'm at a loss.
 

Attachments

  • fig08_38.gif
    fig08_38.gif
    2.2 KB · Views: 442
Physics news on Phys.org
I'm still at a loss for this one
 

Similar threads

Energy conservation equation to find equation for final velocity
  • · Replies 4 ·
Replies
4
Views
1K
Vertical spring & maximum length
  • · Replies 6 ·
Replies
6
Views
1K
Is the line integral of tangential force in pendulum equal to the negative of change in potential energy?
  • · Replies 3 ·
Replies
3
Views
1K
A charge q approaching two stationary charges q1 and q2
  • · Replies 7 ·
Replies
7
Views
1K
Find the launch speed of a ball in a spring mechanism
  • · Replies 8 ·
Replies
8
Views
4K
Finding kinetic energy and initial velocity of a cart over time
  • · Replies 6 ·
Replies
6
Views
2K
Gravitational Potential Energy-Work (ΔU) Question
  • · Replies 4 ·
Replies
4
Views
1K
Conservation of Energy, PE & KE, ball attach to string problem?
  • · Replies 6 ·
Replies
6
Views
15K
Speed of cylinder rolling along a horizontal surface gathering snow (Solved)
  • · Replies 13 ·
Replies
13
Views
2K
Is potential energy defined only for internal conservative forces?
  • · Replies 15 ·
Replies
15
Views
2K