# Understanding Balanced and Unbalanced Forces in Yr11 Physics | Homework Help

• JenL
In summary, the conversation discusses the forces acting on a ball when it is struck by a bat and reaches its highest point. The question is whether these forces are balanced or unbalanced. The forces acting on the ball are gravity and the force from the bat. At the highest point, the ball is momentarily stationary and the forces acting on it are gravity and the force from the bat. The equation Fnet=ma is used to determine whether the forces are balanced or unbalanced, with a net force of 0 indicating balance and a non-zero net force indicating imbalance. The conversation concludes that at the highest point, the forces on the ball are unbalanced due to the force of gravity.
JenL

## Homework Statement

Jackie's team bats later in the day. When Jacki strikes the ball, she hits it badly and it travels straight up.

## Homework Equations

Explain whether the forces are balanced or unbalanced at the highest point.

## The Attempt at a Solution

I thought it was balanced as the ball will be stationary for a moment at the highest point but that was wrong...

It is momentarily stationary, yes, but what are the forces acting on it at that point? Is there a net force?
And oh, welcome to PF!

the question doesn't say if there is a net force but the force acting on the ball are gravity and the force from the bat

JenL said:
the question doesn't say if there is a net force but the force acting on the ball are gravity and the force from the bat
At the instant the ball leaves the bat, the bat is no longer in contact with the ball, so therefore it no longer exerts a force on the ball. So during the flight of the ball, what force (or forces) acts on it? In particular, identify the force(s) acting on the ball at the highest point. Is there an unbalanced net force acting on the ball at that point?

The question does not say if there is a net force or what forces are acting on the ball

JenL said:
The question does not say if there is a net force or what forces are acting on the ball
Quite so, since that is what you are expected to determine. When the ball is lying on the ground, what forces are acting on it? If a ball is falling through the air, what forces are acting on it? What equation do you know relating acceleration of a mass and the net force on it?

Fnet= ma, but I do not understand how this equation will relate to the problem because then the acceleration would be 0 at the highest point. So Fnet= 0 meaning forces acting on the ball are balanced and the answer said that the forces are unbalanced.

Hey There JenL, I think that the acceleration would not be 0 because the gravitational field strength will make the ball accelerate at -10m/s^2 downwards

JenL said:
Fnet= ma, but I do not understand how this equation will relate to the problem because then the acceleration would be 0 at the highest point. So Fnet= 0 meaning forces acting on the ball are balanced and the answer said that the forces are unbalanced.
The velocity is zero at the highest point, but not the acceleration.
You did not answer my question about the forces on a ball lying on the ground. Clearly that does not accelerate, so the forces are balanced in that case. What are they?

Thank you Khemical, that helped. Haruspex, The forces on a ball lying on the ground would be reaction and gravity which would be equal and so balanced. I think I understand the acceleration bit now and the question because wouldn't the acceleration be 10ms^-2 due to the force of gravity. So then Fnet would be unbalanced?

JenL said:
Thank you Khemical, that helped. Haruspex, The forces on a ball lying on the ground would be reaction and gravity which would be equal and so balanced. I think I understand the acceleration bit now and the question because wouldn't the acceleration be 10ms^-2 due to the force of gravity. So then Fnet would be unbalanced?
Exactly.

Thank you :)

## 1. What topics are typically covered in year 11 physics?

Year 11 physics typically covers topics such as mechanics, energy, waves, electricity and magnetism, and atomic and nuclear physics.

## 2. I am struggling with understanding a concept in physics. How can I get help?

There are several ways to get help with year 11 physics. You can ask your teacher for clarification, join a study group with classmates, or seek help from a tutor or online resources.

## 3. How important is it to have a strong foundation in math for physics?

Having a strong foundation in math is crucial for understanding physics. Many concepts in physics require mathematical calculations and equations, so it is important to have a good understanding of math to excel in physics.

## 4. What are some useful study tips for year 11 physics?

Some useful study tips for year 11 physics include practicing problems regularly, taking thorough notes, creating study guides or flashcards, and seeking help when needed. It is also important to stay organized and manage your time effectively.

## 5. How can I prepare for exams in year 11 physics?

To prepare for exams in year 11 physics, it is important to review your notes and practice problems. You can also create study guides or flashcards, and ask your teacher for any specific topics or areas to focus on. It is also important to get a good night's sleep and eat a healthy breakfast before the exam.

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