Science 7.2 Balanced and Unbalanced Forces

Questions and Answers

What are balanced forces? Give an example.

Forces are balanced when they are pushing or pulling equally in opposite directions. An example of a balanced force is two tug of war teams pulling with the same amount of force in opposite directions.

What are unbalanced forces? Give an example.

Forces are unbalanced when one of the push or pull forces is larger than the other. An example of an unbalanced force is a soccer ball rolling towards the goal and changing direction when kicked by the goalkeeper.

What is Net Force?

Net force is the sum of all the forces acting upon an object.

When you push against a brick wall, why doesn't it fall over? Why can a bulldozer push it over?

The wall doesn't fall over because the forces are balanced. A bulldozer can push it over because the forces are unbalanced. Signup and view all the answers

Explain why weightlifters get tired when they hold heavy masses in the air.

Weightlifters get tired because they have to make the reaction force stronger than gravity to create an unbalanced force that lifts their heavy weights. Signup and view all the answers

Give examples of forces that cancel each other out (net force = 0).

If two teams in a tug of war pull with the same amount of force, the net force equals 0, and the forces are balanced. Signup and view all the answers

Give examples of two forces that add together.

Forces acting in the same direction add together, such as two people pushing a cup in the same direction resulting in a net force of 50N. Signup and view all the answers

If Sally can push with 150N and Marilla with 200N in the same direction, with what force can they push?

They can push with 350N. Signup and view all the answers

If Sally can push with 150N and Marilla with 200N, what is the net force if they push in opposite directions?

If they push in opposite directions, the net force is 50N. Signup and view all the answers

Study Notes

Balanced Forces

Balanced forces occur when equal forces are applied in opposite directions.
Example: Two teams in a tug of war pulling with the same force on opposite sides results in no movement.

Unbalanced Forces

Unbalanced forces exist when one force outweighs another, leading to a change in the object's speed, direction, or shape.
Example: A soccer ball moving toward a goal can change direction if a goalkeeper kicks it, creating an unbalanced force.

Net Force

Net force is calculated by summing all individual forces acting on an object, determining its overall effect.

Interaction with Structures

A person pushing against a brick wall does not topple it due to balanced forces.
A bulldozer can push the wall over by applying an unbalanced force greater than the wall's stability.

Weightlifting Challenges

Weightlifters fatigue because they must exert a force greater than gravity to lift heavy weights, creating an unbalanced force.

Examples of Canceling Forces

In a tug of war, if both teams pull with equal force, such as 50N each, the forces cancel out, resulting in a net force of zero.

Examples of Adding Forces

Forces acting in the same direction combine for a greater effect.
Example: Two individuals pushing a cup, one with 25N and the other with 30N, create a net force of 55N.

Combined Forces Calculation

If Sally pushes with 150N and Marilla with 200N in the same direction, their combined force totals 350N.

Opposing Forces Calculation

If Sally's 150N push and Marilla's 200N push are in opposite directions, the net force will be 50N directed towards the stronger force.

Description

This quiz explores the concepts of balanced and unbalanced forces in science. It includes definitions and examples to help reinforce understanding. Perfect for students looking to test their knowledge of physical forces.