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Descrição
Mapa Mental por abbie__lou, atualizado more than 1 year ago
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Criado por abbie__lou
mais de 10 anos atrás
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P4 - Explaining Motion
- Speeding Up and Slowing Down
- A person walking, cars
and bicycles have a
driving force.
- In the case of a car, the
driving force is produced by
the engine.
- The person's muscles
provide the driving force for
someone walking or cycling.
- In the case of a car, the
driving force is produced by
the engine.
- However there is also a counter
force, caused by friction and air
resistance.
- which has the effect of making the
vehicle slow down or stop.
- which has the effect of making the
vehicle slow down or stop.
- If the driving force is bigger than
the counter force, the vehicle
accelerates
- A person walking, cars
and bicycles have a
driving force.
- Forces and Motion
- If more than one force acts on an
object, the forces need to be
added, taking the direction into
account.
- The overall effect of adding all
these forces, taking the direction
into account, is called the resultant
force
- The overall effect of adding all
these forces, taking the direction
into account, is called the resultant
force
- Arrows are used when drawing
diagrams of forces.
- The size and direction of the arrow represents the
size of the force and the direction that it is acting in.
- The size and direction of the arrow represents the
size of the force and the direction that it is acting in.
- If more than one force acts on an
object, the forces need to be
added, taking the direction into
account.
- Momentum
- Momentum is a measure of the
motion of an object.
- The momentum of an object is
calculated using the following formula:
Momentum = Mass (kg) x Velocity (m/s)
- Change in Momentum
- The size of the change in momentum
depends on the size of the resultant
force and the length of time the force
is acting on the object
- The size of the change in momentum
depends on the size of the resultant
force and the length of time the force
is acting on the object
- Momentum is a measure of the
motion of an object.
- Collisions
- If a car is involved in a
collision it comes to a
sudden stop
- i.e. it undergoes a
change in momentum
- If this change in momentum
is spread out over a longer
period of time, the average
resultant force acting on the
car will be smaller
- Example: A car with a mass of
1000kg, travelling at 10m/s has a
momentum of 10,000km m/s
- If the car is involved in a collision and it
comes to a sudden stop, it would experience
a change in momentum of 10,000kg m/s
- If the car is involved in a collision and it
comes to a sudden stop, it would experience
a change in momentum of 10,000kg m/s
- Example: A car with a mass of
1000kg, travelling at 10m/s has a
momentum of 10,000km m/s
- If this change in momentum
is spread out over a longer
period of time, the average
resultant force acting on the
car will be smaller
- This sudden change in momentum will
affect not only the car, but it's
passengers.
- i.e. it undergoes a
change in momentum
- All car safety devices, such as seat
belts, crumple zones and air bags, are
designed to reduce the force of the
impact on the human body
- They do this by increasing
the time of impact
- They do this by increasing
the time of impact
- A crumple zone is an
area designed to 'crumple'
on impact.
- This helps to increase the time
during which the car changes
momentum
- i.e. in stead of coming to a immediate
halt, there will be a longer time during
which the momentum is reduced
- This means that the force exerted on the people inside
the car will be reduced, resulting in fewer injuries
- This means that the force exerted on the people inside
the car will be reduced, resulting in fewer injuries
- i.e. in stead of coming to a immediate
halt, there will be a longer time during
which the momentum is reduced
- This helps to increase the time
during which the car changes
momentum
- If a car is involved in a
collision it comes to a
sudden stop
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