Mechanics Circular Motion Question

In summary, the conversation discusses the concepts of mark scheme method, forces acting on a sphere, contact forces between the sphere and a bowl, and the condition for uniform circular motion. The speaker is confused about the diagram and seeks clarification on how to produce a free body diagram and understand the relevant equations. They also mention feeling unclear about their understanding of the topic.
  • #1
girlwhoneedsmathhelp
7
3
Homework Statement
Q : A small sphere S of mass m kg is moving inside a smooth hollow bowl whose axis is vertical and whose sloping side is inclined at 60◦ to the horizontal. S moves with constant speed in a horizontal circle of radius 0.6 m (attached diagram 1). S is in contact with both the plane base and the sloping side of the bowl (attached diagram 2).
(i) Given that the magnitudes of the forces exerted on S by the base and sloping side of the bowl are equal, calculate the speed of S.
(ii) Given instead that S is on the point of losing contact with one of the surfaces, find the angular
speed of S
Relevant Equations
a = v^2/r OR rw^2
F=ma

As I attempted this question I was very confused and felt my understanding of the topic is unclear and has many gaps. For both parts, I approached the question as I knew the steps I had to do to get the answer but had very little understanding as to why. I managed to get the correct answer for both parts but after looking at the mark scheme felt that my method was off.
If anyone could please help me understand the following questions I would appreciate it very much! Thank you!
Part (i)
1594451188287.png

*Pink represents mark scheme method
Part 2
1594451396860.png

However I am still confused on the diagram.
 

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  • #2
In your "why is this wrong" diagram, you seem to have the force ##mg## coming out of the side of the bowl?

A couple of questions:

How many forces are acting on the sphere?

What does "smooth" tell you about the contact forces between the sphere and the bowl?

What is the condition for uniform circular motion (of a given speed and radius)?

PS I see @archaic has given you part of the answer below.
 
  • #3
Maybe they meant something like this:
d2.png
 
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  • #4
The marker asked how you are defining X. To critique your work, we need to know.
 
  • #5
girlwhoneedsmathhelp said:
... As I attempted this question I was very confused and felt my understanding of the topic is unclear and has many gaps.
...
However I am still confused on the diagram.
Have you learned how to produce a free body diagram (for the ball in this case)?
Do you fully understand the terms and relations shown in the relevant equations of this problem?
 

Related to Mechanics Circular Motion Question

1. What is circular motion?

Circular motion is a type of motion where an object moves along a circular path, with a constant distance from a fixed point. This type of motion can be seen in objects such as a spinning top or a planet orbiting around a star.

2. What is the difference between uniform circular motion and non-uniform circular motion?

In uniform circular motion, the speed of the object remains constant while the direction of motion changes. In non-uniform circular motion, the speed and direction of the object are constantly changing, resulting in varying acceleration.

3. How is centripetal force related to circular motion?

Centripetal force is the force that keeps an object moving in a circular path. It is always directed towards the center of the circle and is necessary for an object to maintain circular motion.

4. Can an object in circular motion have a constant velocity?

Yes, an object in circular motion can have a constant velocity if the speed and direction of the object remain constant. This is known as uniform circular motion.

5. What is the role of angular velocity in circular motion?

Angular velocity is a measure of the rate at which an object is rotating around a fixed point. In circular motion, it determines the speed at which an object travels along the circular path and is related to the linear velocity through the radius of the circle.

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