Anna Hollywood
Flashcards by Anna Hollywood, updated more than 1 year ago
Anna Hollywood
Created by Anna Hollywood over 7 years ago


GCSE Physics (P3) Flashcards on P3, created by Anna Hollywood on 12/02/2013.

Resource summary

Question Answer
Increasing the speed reduces... ...the time needed to cover the same distance
On a distance time graph, what does a steeper gradient mean? A higher speed
What does a straight line on a distance-time graph indicate? That the speed is constant
What does a curved line on a distance-time graph indicate? That the speed is changing
What is a change of speed per unit of time called? Acceleration
The area under a speed-time graph is equal to what? The distance travelled
Is velocity a vector or a scalar? Vector (both size and direction)
How do you work out the relative velocity for two cars that are moving in the same direction? Find the difference
How do you work out the relative velocity for two cars that are moving in different directions? The sum of the individual velocities
Why is a vehicle going round a roundabout accelerating? It has to apply force towards the centre of the circle to keep changing direction
If the forces are balanced at what state is the vehicle? Constant speed or rest
What are the 4 things that increase reaction time for a driver? If they are... tired, under the influence of alcohol/drugs, travelling faster or distracted
What are the 3 things that increase braking distance? -Poor road conditions -Worn brakes -Speed is increased
What are the 3 things that ensure safe driving? -Keeping distance between you and other vehicles -Different speed limits -Slow down in poor conditions
What are the 5 factors that affect braking distance? -Bigger mass=increased BD -Higher speed=increased BD -Worn breaks=increased BD -Worn tyres=increased BD -Increased breaking force=reduced stopping distance
What increases linearly with speed? Thinking distance
What increases as a squared relationship? Braking distance
When is work done? When a force moves an object in the direction in which the force acts
What is weight a measurement of? The gravitational attraction on a body acting towards the centre of the Earth
What is power? The rate at which work is done
A persons power is greater when they run than when they walk. True or false? True
What does the power rating of a car depend on? Its engine size
How does the braking distance of a car increase? With increasing speed (but not proportionally)
What happens to a car's K.E when it stops? It changes into heat in the brakes, tyres and road.
Work done by brakes= Loss in K.E
Braking force x braking distance = Loss in K.E
What happens to the K.E and the braking distance when the speed of the car doubles? They quadruple
What are the 5 factors that affect the fuel consumption of a car? -amount of energy needed to increase its K.E -Amount of energy needed to do work against friction -speed -how it's driven -road conditions(rough)
What are 4 issues with electric cars (solar powered and battery driven)? -Battery is large -Limited range before they need recharging -Expensive to buy -Rely on sun
What are two advantages of electric cars? -They don't (directly) pollute -Cost of recharging is low
How do battery powered cars indirectly pollute? Recharging the batteries requires electricity from power stations which pollute
Although biofuels may reduce carbon emissions, why is this not certain? Because deforestation leads to an increase in CO2 levels
What spreading momentum change over a long time do? Reduces the force
How can we reduce acceleration (and therefore force)? -Increasing stopping/collision time -Increasing stopping/collision distance
What are the 5 features that reduce acceleration? -Crumple zones -Seat belts -Air bags -Crash barriers -Escape lanes
What do modern cars have that help absorb energy in a crash (4 things)? -Brakes that get hot -Crumple zones that change shape -Seat belts that stretch -Air bags that inflate and squash
Why does seat belts stretching help absorb energy? Converts K.E into elastic energy
What are the 3 reasons why drivers don't like wearing seatbelts? -Risk of chest injury -Could be trapped in fire -Could encourage driver to drive more carelessly as he/she knows they're protected by seatbelt
What is the best way to gain safety information? By using crash tests with real vehicles and dummies
What are ABS brakes? A primary safety feature which helps to prevent a crash
How does the ABS system work? Wheel-speed sensors send information to a computer about the rotational speed of the wheels. The computer controls the pressure to the brakes to prevent the wheels locking up. This increases the braking force just before the wheels start to skid
What are two other primary safety features? -Cruise control (stops a driver becoming tired and pressing harder on the accelerator) -Electric windows and paddle shift controls (allows driver to concentrate on road)
What are the two things that affect the size of air resistance? Cross sectional area and speed
When does air resistance only have effect? When it is large compared to the weight
What is the journey of a parachutist like in terms of forces? 1)Accelerates, displacing more air molecules a second. Air resistance increases, reducing his acceleration 2)Weight and air resistance are equal = terminal speed 3)Parachute opens and air resistance increases due to large surface area. Parachutist decelerates and air resistance decreases 4)New lower terminal speed
What are three qualities of the gravitational field strength? -Unaffected by atmospheric conditions -Varies with position on the Earth's surface -Varies with height above/below Earth's surface
What does an object held above the ground have? Gravitational potential energy
What are the 4 steps of a bouncing ball? 1)Ball has GPE but no K.E 2)Reached ground-has K.E but not GPE 3)Ball squashes-has EPE-converted to K.E as it leaves ground 4)At top of bounce has GPE
What is the loss in GPE in a skydiver due to? The work against friction (air resistance)
change in GPE = work done against friciton
What do the riders at the top of a roller coaster ride have? GPE
What happens when the roller coaster is released? Converts GPE into KE as it falls
Loss in GPE= Gain in KE
Why does each peak in a roller coaster have to be lower than the one before? Because some energy is transferred to heat and sound due to friction and air resistance
GPE at top of roller coaster= KE at bottom + energy transferred due to friction
If speed doubles what happens to KE? It quadruples
If mass doubles, what happens to KE? It doubles too
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