Kinetic and Potential Energy calculation

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SUMMARY

The discussion focuses on calculating kinetic and potential energy for a particle in a smooth hemispherical bowl. The particle, with a mass of 0.215 kg, is released from rest at point A, and the calculations involve gravitational potential energy (PE) and kinetic energy (KE) at points B and C. The correct application of conservation of energy reveals that the kinetic energy at point C is 0.211 J, contrasting with the incorrect calculation of 0.43 J. The established formulas used include PE = mgh and KE = 1/2 mv².

PREREQUISITES
  • Understanding of gravitational potential energy (PE) and kinetic energy (KE) formulas
  • Basic knowledge of conservation of energy principles
  • Ability to perform unit conversions (grams to kilograms, centimeters to meters)
  • Familiarity with basic physics concepts related to motion and forces
NEXT STEPS
  • Study the principles of conservation of mechanical energy in physics
  • Learn how to apply energy conservation in different physical systems
  • Explore the derivation and application of the kinetic energy formula KE = 1/2 mv²
  • Investigate potential energy calculations in various gravitational fields
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This discussion is beneficial for physics students, educators, and anyone interested in understanding energy calculations in mechanics, particularly in systems involving gravitational forces.

Blubla
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A 215 g particle is released from rest at point A inside a smooth hemispherical bowl of radius 30.0 cm. Point B to C have Height= 2/3(R)
Calculate the following: A. The gravitational potential energy at A relative to B
B. The particle's kinetic energy at B
c. Th particle's speed at B
D. The potential energy and kinetic energy at C

I solved A,B,C and D(The potential Energy but not the kinetic energy)

Here is my work:

A. Changed 215 g into Kg so it will be 0.215 kg
30.0 cm into m so it will be 0.30m
PE=mgh
PE=0.215*9.81*0.30
PE=0.633J
B. KE= 1/2mv^2
KE=1/2*0.215*2.4^2
KE=0.62JC. V^2f=2gh
V^2f=2*9.81*030
V^2f=5.9 Apply square root
Vf= 2.4m/s

D. PE=mgh
PE=0.30*9.8(2/3*0.30)
PE=0.422

Can someone please help me find the KE at C, the answer is 0.211J according to the book. Well, what I got is 0.43J..
Thanks in advance.
 
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You missed the point of the problem. Use conservation of energy.
 
That is true, you need to use the conservation of energy between C and B.
mgR= KEc + mg(2/3)R
KEc=1/3mgR=0.211J
 

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