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P2 (1) (Velocity and Acceleration (Using Velocity time graphs (Show how an…
P2 (1)
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Terminal Velocity
Drag forces increases as an object moves faster(every moving object experiences and force in the opposite directions)
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Skydiver
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As they accelerate, drag forces match his weight and he reaches a top speed(terminal velocity)
When the parachute is opened, drag forces increase, the resultant upwards forces decelerates and drag force decrease until he reaches a slower terminal velocity
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Forcing it
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Using Resultant Forces
In a vehicle, fuel consumption increases if drag forces increases at a certain speed
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Forces and Acceleration
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Mass in Space
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To find mass in space, a known force as to be applied and the acceleration need sot be measured
Balanced Forces
Forces on Moving Objects
For every force, there is an equal sized force acting in the opposite direction
EG
When sitting on a chair, it pushes as hard as you push down on it
When a parachute is pulled, the weight of the diver is matched by the upwards tension in the parachute strings
Lift
When a lift accelerates upwards, the force from the floor pushing upwards is greater than the weight of the person is lifted. The person feels heavier than normal
Stop
Thinking and Braking
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Thinking Distance = Speed x Reaction time(increases if the driver is tired, distracted or has taken alcohol or drugs)
Braking distance = distance travelled while the brakes are applied(increases if the road is wet or icy, the tyres are worn down, brakes are in bad conditions)
Aquaplaning
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If the tyre thread is worn, water cannot be removed so the car slides over a layer of water on the road and cannot be controlled
Forces and Elasticity
Elastic Object
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above the limit, extension is not proportional to the force
Hooke's law 
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Energy to Move
Kinetic Energy transfers
Transferred by- From chemical energy in food a person eats, From chemical energy in fuel used in an engine
Kinetic Energy is transferred to the surroundings as a result of frictional forces- Friction between car tyres and the road surfaces, Air resistance felt by aircraft and other moving objects
Kinetic Energy transfer can be useful- Regenerative breaks slow down the car using the engine(used to charge the battery's), In a car crash, car crumble zones are designed to distort, absorbing kinetic energy
Storing Kinetic Energy
Flywheels are heavy, fast-spinning wheels that store kinetic energy for short periods of time
Working Hard
How Much and How Far?
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Work is done, and energy is transferred whenever a force moves
A smaller force is needed to drag something up a ramp compared with lifting it directly. The force along the ramp is working over a longer distance, and also needs to work against friction
The clock's stopped!
When the battery runs out, clocks stop with their moving hands in the 'quarter to' position. Most work must be done to lift the hand upwards per tick in this position
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