P6 Forces

Forces

Primary 6 Love

Open Ended

Name as many forces that you know of.

Frictional Force

• •Frictional force is a contact force.

  •It is present when two surfaces are in contact.

  •It can slow down or stop a moving object as it acts in the opposite direction of motion.

Factors Affecting Frictional Force

•Texture of a surface affects frictional force.

•Greater frictional force between a moving object and a rough surface than between the object and a smooth surface.

 

*Note the direction of the arrows

Multiple Choice

Do you think an object will move further on a smooth surface or a rough surface?

• Smooth surface

• Rough surface

• Same distance for both

Open Ended

Two identical blocks, A and B, are placed on the floor as shown above. They are then pushed across the floor with the same amount of force. Will there be a greater frictional force between the ground and block A, or the ground and block B? Why?

Open Ended

Do you think that frictional force is good or bad for us? Why?

Advantages of Frictional Force

•Frictional force helps to slow down or stop a moving object.

•It helps us to grip objects without dropping them.

•It prevents us from slipping and falling when we are walking.

Disadvantages of Frictional Force

•Frictional force can cause moving objects to slow down.

•It also causes objects to overheat or wear-and-tear

•We can use lubricants such as oil, grease or water to reduce the frictional force between two surfaces.

•Wheels and ball bearings can also be used.

Open Ended

Drivers are encouraged to keep a safe distance from the vehicle ahead of theirs while driving. Why should they increase this distance on a rainy day?

Elastic Spring Force

•A material is elastic if it is able to return to its original shape after a force applied on it is removed.

•When we pull a spring and then let go of it, it returns to its original shape. The spring is elastic.

•When we pull or push a spring, it gets stretched or compressed.

•Elastic spring force is exerted by the stretched or compressed spring. 

Factors Affecting Elastic Spring Force

•Greater elastic spring force is exerted by the spring that is stretched or compressed more.

•When a greater force is applied on a spring, the extension of the spring increases. 

Multiple Choice

Four identical blocks were attached to a table top using three identical springs. Which of the following would be the correct amount of compression for each spring?

Gravitational Force

•Gravitational force is the force of attraction between objects.

•It can act from a distance.

•It pulls all objects towards the centre of the Earth.

•This prevents us from floating in the air.

 

Gravitational Force

•It causes objects to fall downwards.

•It is harder to climb up a hill as the movement is in the opposite direction of gravitational force.

•It is easier to go down a slope as the movement is in the same direction as gravitational force. 

Weight Vs Mass

Multiple Select

The diagram on the left shows three identical balloons in three situations. At which situation(s) does gravity act on the balloon?

• deflated balloon

• balloon filled with air

• balloon filled with helium

Fill in the Blanks

Poll

Which of the following forces are you still unsure of? (You can tick more than one)

• Frictional Force

• Elastic Spring Force

• Magnetic Force

• Gravitational Force