Balance and Unbalanced Force

What is the relationship between friction and force?

• Friction has no relationship with force.

• Friction is the force that causes an object to change shape.

• Friction is the force that accelerates the motion of an object.

• Friction is the force that opposes the motion of an object.

Can you provide an example of balanced forces in everyday life?

• Leaving a book on a table

• Pulling a stationary object from one side only

• Pushing a stationary object with the same force from opposite sides

• Pushing a stationary object with different forces from opposite sides

Explain the concept of unbalanced force with an example.

• When a soccer ball is kicked, the force applied to the ball is balanced, causing it to stay still.

• When a soccer ball is kicked, the force applied to the ball is unbalanced, causing it to accelerate and move in the direction of the kick.

• An unbalanced force is when two equal forces act on an object in opposite directions.

• An example of unbalanced force is when a car is moving at a constant speed on a straight road.

Draw a force diagram for a book resting on a table.

• Draw a force diagram with an upward force of gravity and a downward normal force from the table

• Draw a force diagram with a downward force of gravity and an upward normal force from the table.

• Draw a force diagram with a downward force of gravity and a rightward force

• Draw a force diagram with only a leftward force

How does friction affect the motion of an object?

• Friction has no effect on the motion of an object.

• Friction speeds up the motion of an object.

• Friction causes the object to float in the air.

• Friction slows down the motion of an object.

Give an example of balanced forces acting on an object in motion.

• A rocket accelerating into space

• A bicycle slowing down on a hill

• A ball rolling down a hill

• A car moving at a constant speed on a straight road

Describe a situation where unbalanced forces cause an object to accelerate.

• Inertia and momentum provide unbalanced forces on a moving train on a straight track.

• Gravity and magnetism provide unbalanced forces on a stationary book on a table.

• Buoyancy and tension provide unbalanced forces on a floating object in water.

• Friction and air resistance provide unbalanced forces on a car accelerating on a road.

Create a force diagram for a car moving at a constant speed.

• Balanced forces

• Friction and air resistance

• No forces acting on the car

• Unbalanced forces

What are the factors that affect the amount of friction between two surfaces?

• Age of the surfaces, sound, brightness

• Color of the surfaces, temperature, humidity

• Roughness of the surfaces, force pressing the surfaces together, types of materials in contact

• Size of the surfaces, smell, taste

Explain how balanced forces result in no change in an object's motion.

• The net force is unbalanced, resulting in no change in the object's motion.

• The net force is negative, resulting in no change in the object's motion.

• The net force is doubled, resulting in no change in the object's motion.

• The net force is zero, so there is no change in the object's motion.