- #1
reree17
- 17
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Seriously confused, please help!
Hi there. These are just a few questions I just can’t get my head around. I don’t understand HOW:
a) HOW an air bag reduces injury exactly – Question says ‘Explain how an air bag reduces the risk of head injury in an accident’ – I know that the air bag inflates so it blocks the driver’s access to the steering wheel and thus reducing the risk of head injury, but how can I explain this more scientifically?
b) Calculate the average braking force acting on a car of 800 kg to bring it to rest if it was traveling at 20 m/s – I used the equation F= M X A (Mass x Acceleration). So speed is measured in m/s right? And acceleration is measured in m/s squared? So would I do 800 x 20 squared = 320,000 N or just leave it at 20 m/s?
c) [URL]http://postimage.org/image/1spa51pic/[/URL] – Sorry the picture is a bit blurry, in case you can’t read it it says ‘The circuit below is used to investigate how the resistance of a lamp changes. Explain how component X allows a set of results to be obtained. – I wrote that Component X is a variable resistor and therefore varies the current. The higher the current the lower the resistance and the lower the current the higher the resistance – Is this the right answer? How can it be improved?
d) [URL]http://postimage.org/image/1mxtsq344/[/URL] – Explain how the graph shows that the resistance of the lamp increases as the voltage increases – Following Ohm’s Law, The higher the current, the higher the voltage right? But the higher the current, the lower the resistance? And the higher the voltage the lower the resistance? So why does the resistance increase as the voltage increases?
e) Explain how the miniature circuit breaker protects against fire – I know that the electromagnets in the mcb become strong enough to separate a pair of contacts, but how exactly does separating a pair of contacts protect against a fire?
f) Explain how the residual current device protects the user – I know that the rcd detects a difference in the currents in the live and neutral wires but how does this protect the user? Does it break the circuit or trip the circuit? And what exactly does tripping a circuit mean?
These are just few problems from practice papers I found difficult, I’m trying to understand them to help prepare for my exam. Thanks so so so so much for answering in advance!
Hi there. These are just a few questions I just can’t get my head around. I don’t understand HOW:
a) HOW an air bag reduces injury exactly – Question says ‘Explain how an air bag reduces the risk of head injury in an accident’ – I know that the air bag inflates so it blocks the driver’s access to the steering wheel and thus reducing the risk of head injury, but how can I explain this more scientifically?
b) Calculate the average braking force acting on a car of 800 kg to bring it to rest if it was traveling at 20 m/s – I used the equation F= M X A (Mass x Acceleration). So speed is measured in m/s right? And acceleration is measured in m/s squared? So would I do 800 x 20 squared = 320,000 N or just leave it at 20 m/s?
c) [URL]http://postimage.org/image/1spa51pic/[/URL] – Sorry the picture is a bit blurry, in case you can’t read it it says ‘The circuit below is used to investigate how the resistance of a lamp changes. Explain how component X allows a set of results to be obtained. – I wrote that Component X is a variable resistor and therefore varies the current. The higher the current the lower the resistance and the lower the current the higher the resistance – Is this the right answer? How can it be improved?
d) [URL]http://postimage.org/image/1mxtsq344/[/URL] – Explain how the graph shows that the resistance of the lamp increases as the voltage increases – Following Ohm’s Law, The higher the current, the higher the voltage right? But the higher the current, the lower the resistance? And the higher the voltage the lower the resistance? So why does the resistance increase as the voltage increases?
e) Explain how the miniature circuit breaker protects against fire – I know that the electromagnets in the mcb become strong enough to separate a pair of contacts, but how exactly does separating a pair of contacts protect against a fire?
f) Explain how the residual current device protects the user – I know that the rcd detects a difference in the currents in the live and neutral wires but how does this protect the user? Does it break the circuit or trip the circuit? And what exactly does tripping a circuit mean?
These are just few problems from practice papers I found difficult, I’m trying to understand them to help prepare for my exam. Thanks so so so so much for answering in advance!
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