P10 Flashcards
What is Newton’s 2nd law
The acceleration of an object is proportional to the resultant force on the object and inverserley proportional to the mass of the object
What is resultant force
Mass x Acceleration
What is the inertia of an object
The tendency to stay at rest or in uniform motion
What is the difference between mass and weight
Weight of an object is the force acting on the object due to gravity, the mass is the quantity of matter in the object
What is the motion of a falling object acted on only by gravity
It would accelerate at about 10 m/s squared
What does terminal velocity mean
The velocity it will eventually reach when it’s falling
What can be said about the resultant force acting on an object that is falling at terminal velocity
When an object is moving at terminal velocity the resultant force is zero
What are the forces that oppose the driving force a vehicle
Friction an air resistance
What does the stopping distance of a vehicle depend on
Thinking and braking distance
What can increase the stopping distance of a vehicle
High speed, poor weather conditions, and poor vehicle maintenance, high speed, poor reaction time ( due to tiredness alcohol drugs or on your mobile phone )
How do you estimate the braking force of the vehicle
Mass times acceleration
How do you calculate momentum
Mass x velocity = P Kg m/s
Why did two objects that push each other apart move away at different speeds
If they have unequal masses, and with equal and opposite momentum
What is the conservation of momentum equation
Mass of a X velocity of a + mass of B X velocity of B
What affects the force of impact when two vehicles collid
Mass, change the velocity, and the length of the impact time
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Impact force depends on the impact time
What can be said about the impact forces and the total momentum when two vehicles collide
They exert equal and opposite forces on each other, the total momentum is unchanged
Why does impact force depend on the impact time
Impact force = change in momentum / impact time, so shorter impact time means greater impact force
Why do you cycle helmets and cushion services reduce impact forces
Because they increase the impact time
Why do you seat belts and airbags reduce the force on people in car accidents
They spread the force across the chest and increase the impact time
How does impact bars and crumple zones work
They increase impact time
How to work out if a car in a collision was speeding
Using conservation of momentum to find the speed before the accident
What is meant when an object is called elastic
If the objects can return to its original shape after removing the force deforming it in the first place
How do you measure the extension of an object when it’s stretched
Original Length - new length = extension
How does the extension of the spring change with the force applied to it
The extension of a spring is directley proportional to the force applied to it
What is meant by the limit of proportionality of a spring
The extension of the spring is no longer proportional to the applied force
