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How do you calculate the work done by moving an object through a distance?
Work = Force x distance
What is the unit of energy?
What name do we give to how quickly energy is transferred?
What is the standard unit of time?
What is the unit of power?
- Watt (W)
- (1 Watt = 1 Joule per second)
What affects an object's Gravitational Potential Energy?
- Its height from the ground,
- the strength of gravity
What affects an objects kinetic energy the most?
- (doubling the velocity quadruples the KE)
What is the standard unit for mass?
How is the momentum of an object calculated?
Mass x velocity
What is the difference between speed and velocity?
- Speed just has a size.
- Velocity has a size and a direction (a vector)
What does conservation of momentum mean?
In a closed system, the total momentum before an event is equal to the total momentum after the event
What affects thinking distance AND stopping distance?
When an object is lifted up, what type of energy is it given?
Gravitational Potential Energy (GPE)
What name is given to the energy of a moving object?
Kinetic Energy (KE)
When an object falls from a height, what energy transfer takes place?
GravitationalPotential Energy (GPE) is converted to Kinetic Energy (KE)
What effect will alcohol and other drugs have on braking distance?
They will only affect thinking distance (which will affect stopping distance)
When a vehicle brakes and slows down, what has happened to the lost Kinetic Energy?
It has been converted to thermal energy (heat) in the brakes and is dissipated (lost to the surroundings)
What is the relationship between
stopping, braking and thinking distances?
- Stopping distance = thinking distance + braking distance
What does thinking distance mean?
The distance you travel whilst your brain is thinking about applying the brakes
Name three things that can affect a driver's thinking distance?
- Alcohol / other drugs
- Distraction (eg on telephone, fiddling with radio)
When vehicle brakes are applied and the vehicle loses kinetic energy, where does the energy go?
Friction between the brakes and the wheel increases the temperature of the brakes
Name three things that can affect a vehicle's braking distance
- Adverse weather conditions (wet or icy)
- Poor condition of vehicle (brakes & tyres only - not whether it is dirty/ rusty/ the winscreen wiper don't work!)
What is the equation to calculate GPE?
What do seat belts, crumple zones and air bags all do to reduce injury?
They increase the time it takes for the person to stop moving so reduce the force on the person. (This reduces injury)