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Science P2 Topic 4
Edexcel GCSE additional science physics: momentum, energy, work and power
|What is the stopping distance and what is it made up of?
|The stopping distance is the distance covered from when you realise you have to stop to when the breaks bring the vehicle to a halt- it is made up of the thinking distance + the braking distance
|What is the thinking distance and how do you calculate it?
|Thinking distance is the distance covered from when you realise you have to stop to when you react and hit the breaks- thinking distance = driver's reaction time X speed of vehicle
|What is the braking distance?
|The distance covered from when the breaks are pressed to when they bring the vehicle to a halt
|What factors affect the stopping distance?
|* driver's reaction time (affected by fatigue, drugs, illness) * condition of the road surface * condition of the tyre * friction between the tyre and road surface * speed of the vehicle * mass of the vehicle
|What is momentum?
|The amount of mass in motion or how difficult it is to stop a moving object, measured in kg.m/s
|Is momentum a vector or scalar quantity and why?
|A vector quantity as it has a size and a direction (the direction of the velocity)
|What is the conservation of linear momentum?
|The idea that momentum is conserved at collisions
|100kg skateboarder travels at 5m/s, crashes into stationary trolley with 10kg mass- if the skateboarder keeps going in the same direction at 2m/s, what is the speed of the trolley after the collision?
|What are some examples of vehicle safety measures and what do they try to do?
|all vehicle safety measures try to reduce the rate of change of momentum to reduce the force of the crash on the passenger: seat belts, crumple zone, air bags
|Why is bubble wrap used?
|It is used to pack fragile items as it decreases the rate of change of momentum when dropped, because the bubbles slowly compress, reducing impact
|What is needed to change the momentum?
|A force (equal to the rate of change of momentum)
|What is work?
|Work is done when energy is transferred from one form to another, measured in joules
|What is power in relation to work?
|Power is the rate of doing work, measured in watts
|1 watt = ? (in relation to work)
|1 joule of work per second
|how do you calculate how much work must be done to stop a vehicle?
|work done = braking distance X braking force
|What is the work done to stop a moving vehicle equal to?
|The initial kinetic energy
|What is gravitational potential energy?
|Energy that is stored due to an object’s position in a gravitational field
|What is the strength of the gravitational field strength on earth?
|What is kinetic energy?
|For a falling object: the initial amount of gravitational potential energy = ?
|The kinetic energy when the object hits the ground