Energy conservation in circular motion

[Fatima Hasan]

Homework Statement

An object of mass m = 1 kg moves along a circular frictionless path of radius R = 0.5 m from point A to point B at which it makes an angle θ with the vertical direction as shown in the figure. If the object is release from rest (VA = 0) and θ = 30° , what is the normal force at point B (in N) ?

A ) 2.98 B) 25.98 C) 28.19 D) 29.54

Homework Equations

3. The Attempt at a Solution [/B]
Here's my work :

 

[ehild]

Homework Statement

An object of mass m = 1 kg moves along a circular frictionless path of radius R = 0.5 m from point A to point B at which it makes an angle θ with the vertical direction as shown in the figure. If the object is release from rest (VA = 0) and θ = 30° , what is the normal force at point B (in N) ?
View attachment 217967

A ) 2.98 B) 25.98 C) 28.19 D) 29.54

Homework Equations

View attachment 217968

3. The Attempt at a Solution [/B]
Here's my work :
View attachment 217969

Your work is wrong. What is k?
You can not write gh=gh+0.5v^2. It means that the v²=0.

 

[Fatima Hasan]

Your work is wrong. What is k?
You can not write gh=gh+0.5v^2. It means that the v²=0.

K is a typo. It should be m
gh1 = gh2 + 0.5 v^2

 

[ehild]

K is a typo. It should be m
gh1 = gh2 + 0.5 v^2

It is better now, but your v²is wrong.

 

[Fatima Hasan]

It is better now, but your v²is wrong.

I found the mistake. The height in B, I should substract it from 0.5
The answer is 25.98

 

[ehild]

I found the mistake. The height in B, I should substract it from 0.5
The answer is 25.98

Well done!