Transcript
How are forces and motion related? Chapter
11: Lesson 1:
Motion
Change in position
Types of motion
1) Up and down
motion
2) Straight line motion
3) Round
and round motion
4) Zigzag motio
n
5) Back and
forth motion
1) Up and down motion
2) Straight line motion
3) Round and round motion
4) Zigzag motion
5) Back and forth motion
Motion can be:
Fastand
Slow
motion
motion
Same direction
Or
Change direction
Draw arrows on the following pictures showing the type of motion.
Activity
DistanceHow far it is
from one position to
another position
Measure the distance of the arrows shown using a ruler or a measuring tape.
Activity
1
43
2
5
DirectionAn object can
move north, south, east or
west.
ForcesA push or a
pull.Example:- When you open a door
(pull)- When you close a drawer
(push)- When you are kicking the
ball (push)
A force can:
1) Make something move
2) Change
the direction
of a moving object
3) Change
the speed of a moving
object
4) Change
and objects shape
Types of forces:
1) Balanc
ed forces
2) Unbalanced
forces
1) Balanced ForcesForces that cancel each
other when acting together on a single
object.Example:
Both forces
are equal so the object
does not move
Balanced forces do not change motion.
- If an object is not moving it will not move.
- If an object is moving it will continue to move in the same direction without changing speed.
2) Unbalanced
ForcesForces that are not equal
to each other .- It causes a change in motion.- The greater force determines
the direction of motion.- Unbalanced forces can make
and object start to move, speed up, slow down or change directions.
GravityThe force that
makes things fall to the ground on
earth.
Mass vs. Weight- How much
matter in an object.
- Measured by g or kg
(not a force)
- Force caused by gravity
pulling down on the mass of
an object.- Measured in Newton (N)
How can we measure weight?Weight is measure using
a force meter.
• Friction is a force between two surfaces that are sliding, or trying to slide across one another, for example when you try to push a toy car along the floor.
• Friction always works in the direction opposite from the direction the object is moving, or trying to move. It always slows a moving object down.
Moving
Friction
• Friction also produces heat. For example, if you rub your hands together quickly, they get warmer.
• The amount of friction depends on the materials from which the two surfaces are made. The rougher the surface, the more friction is produced. For example, you would have to push a book harder to get it moving on a carpet than you would on a wooden floor. This is because there is more friction between the carpet and the book than there is between the wood and the book.
• Friction can be a useful force because it prevents our shoes slipping on the pavement when we walk and stops car tyres skidding on the road.
• Ice causes very little friction, which is why it is easy to slip over on an icy day. But this is a good thing for ice skating and sledging.
• Sometimes we want to reduce friction. For example, moving parts inside a car engine are lubricated with oil, to reduce friction between them. The oil holds the surfaces apart, and can flow between them. The reduced friction means there is less wear on the metal, and less heat produced.
• Air resistance is a type of friction between air and another material. When an aeroplane flies through the air, for example, air particles hit the aeroplane, making it more difficult for the aeroplane to move through the air.
• Some shapes, known as streamlined shapes, cause less air resistance than others. Aeroplanes and cars are streamlined, so that they move through the air as easily as possible.
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