P1.4 Flashcards
What is the thinking distance
The distance the vehicle travels while the driver processes brakes need applying
What is the braking distance
Distance vehicle travels once brakes are applied to when it’s stops
What is stopping distance
Thinking distance plus braking distance
What can affect thinking distance
How fast the reactions of the driver are
If the driver has had any drugs such as caffeine or alcohol
How fast the vehicle is travelling, faster it is, the greater the thinking distance
What affects braking distance
How fast vehicle is, if it’s fast, it will take longer to stop so travel further
The condition of the brakes and tires, worn ones won’t apply as much friction so won’t stop the vehicle so fast
Condition of road, if it’s wet, it will take longer than if it’s dry
How heavy it is, if it’s heavier, more force will be needed to stop it so it will travel further
What is momentum and it’s formula
It’s a measurement of how much force is in something moving, how strongly it’s moving
Momentum kg m/s = mass kg * velocity m/s
It is a vector quantity and is in the same direction as the velocity
What does it mean by saying momentum is conserved
When two objects collide, there total momentum will be equal to the total momentum of the two objects before they collided. Momentum is always the same before and after the collision, it’s conserved
How do crumple zones work
They slow down the rate in which a vehicle comes to a full stop, slow its deceleration so it’s spread over a longer time. This means the force applied is less as the time for the force to be applied is longer
How do vehicles reduce the force applied to you in a collision and why
By reducing the force applied in a collision, the chance of damage and injury is reduced. To reduce the force, the time for the change in momentum is increased to reduce the force. Seat belts, crumple zones and air bags are all ways used to increase time for change in momentum
Formula for force needed to change momentum in a certain amount of time
Change in momentum Kgm/s / time s
Change in momentum is final momentum - initial momentum. This can be negative
What is work
The amount of energy transferred from one form to another, as it’s a measurement of energy, it’s measured in joules j
Formula for work done
Work done = force * distance moved in direction of force
Joules = newtons * meters
What is power
The rate of which work is done, how much energy is transferred per second and measured in watts
Power W = work done J / time S
What is gravitational potential energy
The amount of energy stored in an object based on its position in the gravitational field. It’s equal to the amount of energy released when the object falls.
Formula for GPE
GPE J = mass Kg * gravitational field strength N/Kg * vertical height M
