Friction applications

Q uestion one: Complete the following:

1- Friction forces can be observed in ……… , ……… and ……… .

solids – liquids – air  

2 - The friction forces can be observed in air only when the objects move ……… .

so fast  

3 - Air crafts, rockets and trains are having ……… shape to overcome ……… force.

Streamline – friction

4 - The friction in air is known as ……… while friction in water is known as ………

air resistance – water resistance  

5 - There is a ……… relation between friction and ……… of a moving object.

direct – surface  

6 - The car is said to be moving by constant velocity when ……… force equals ……… force.

motion – friction  

7 - The friction force affects in ……… direction of movement.

opposite  

8 - As the body moves fast in water, its resistance ……… .

increases  

9 - The fish has ……… shape to decrease ……… .

streamline – friction  

1 0- Friction prevents people from ……… during walking.

slipping down  

1 1- Lightening of a match depends on ……… force.

friction

1 2- By friction force cars can move ……… .

forward  

1 3- The car tyres contain ……… to increase friction.

grooves

Q uestion two:

Write three advantages of friction.

1- Car can move forward. 2- People can walk. 3- Lightening of a match.  

Q uestion three: Give reasons for:

1- Rockets and aircrafts have streamlined shape.

To decrease friction force with air.  

2 - The fish has streamline shape.

To decrease friction force with water.  

3 - People can walk on the ground.

Due to the presence of friction force.  

4 - Fast boats are designed in small surface.

To decrease friction force with water.  

5 - Friction can be observed only in fast objects in air.

Because air has small mass.  

Q uestion four: Comparison:

Compare between air resistance and water resistance.

Q uestion five:

"Friction is one of the basic forces". Explain.

Because it is used in many objects to move and change speed or direction.