Show that the initial speed is vi = sqrt 2gL(l-cosθ).

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SUMMARY

The discussion centers on deriving the initial speed of an object suspended from a cart, specifically showing that the initial speed is given by the equation vi = sqrt(2gL(l - cosθ)). The problem involves a mass m suspended by a string of length L, which swings through an angle θ after the cart comes to rest. The key equations utilized include the conservation of kinetic energy (KE) and potential energy (PE), specifically 1/2mv² = mgh. The discussion also provides a specific example with L = 2.0 m and θ = 40.0° to calculate the initial speed.

PREREQUISITES
  • Understanding of basic physics concepts such as kinetic energy (KE) and potential energy (PE).
  • Familiarity with trigonometric functions, particularly cosine.
  • Knowledge of the conservation of energy principle.
  • Ability to manipulate algebraic equations and solve for variables.
NEXT STEPS
  • Study the derivation of energy conservation equations in physics.
  • Learn about the application of trigonometry in physics problems involving angles and lengths.
  • Explore examples of pendulum motion and the factors affecting its swing.
  • Investigate the effects of different angles on the potential energy of suspended objects.
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone interested in understanding the principles of energy conservation and motion in mechanics.

alevis
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Homework Statement


An object of mass m is suspended from the top of a cart by a string of length L. The cart and object are initially moving to the right at a constant speed vi. The cart comes to rest after colliding and sticking to a bumper, and the suspended object swings through an angle θ.
(a) Show that the initial speed is vi = sqrt 2gL(l-cosθ).
(b) If L = 2.0 m and θ = 40.0°, find the initial speed of the cart.


Homework Equations


KE = PE
1/2mv2 = mgh
L1= L-(Lcosθ)


The Attempt at a Solution


1/2mv2 = mgh
v2 = 2mgh/m
v = sqrt 2gh
stuck!
 
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Did you draw a diagram? Look at the situation. How can you express the height the object moves through in terms of the length of the string?
 

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