Hard physics question
Can anyone help with this please:
A pebble is dropped from a height level with the end of a diving board above a lake. The velocity of the pebble immediately before it hits the surface of the water is 12m/s. Calculate the height of the diving board.
The only answer i can think of is 12 (Got that by getting time as 1 second)
but I don't think that's right.
A pebble is dropped from a height level with the end of a diving board above a lake. The velocity of the pebble immediately before it hits the surface of the water is 12m/s. Calculate the height of the diving board.
The only answer i can think of is 12 (Got that by getting time as 1 second)
but I don't think that's right.
Original post by LittleBoxes
Can anyone help with this please:
A pebble is dropped from a height level with the end of a diving board above a lake. The velocity of the pebble immediately before it hits the surface of the water is 12m/s. Calculate the height of the diving board.
The only answer i can think of is 12 (Got that by getting time as 1 second)
but I don't think that's right.
A pebble is dropped from a height level with the end of a diving board above a lake. The velocity of the pebble immediately before it hits the surface of the water is 12m/s. Calculate the height of the diving board.
The only answer i can think of is 12 (Got that by getting time as 1 second)
but I don't think that's right.
7.3m
use v^2 = u^2 + 2as
btw the answer will be different depending on your value of g. I used g = 9.81
first step a little diagram.
mark your positive direction
mark distance as x or s (whatever you are used to using)
a=9.81ms or -9.81ms depending on your diagram
u=0m/s v=12m/s
do a suvat
t is missing
so I think we use v^2=u^2+2as
you have to do a suvat, you have to have a little cheat sheet with you until you memorise all the equations of motion. You might be given them on the formula sheet.
mark your positive direction
mark distance as x or s (whatever you are used to using)
a=9.81ms or -9.81ms depending on your diagram
u=0m/s v=12m/s
do a suvat
t is missing
so I think we use v^2=u^2+2as
you have to do a suvat, you have to have a little cheat sheet with you until you memorise all the equations of motion. You might be given them on the formula sheet.
(edited 7 years ago)
Isn't it just v^2 = u^2 +2as.
Where v = 0's^-1
u = -12 ms^-1
a = -9.8ms^-1
Posted from TSR Mobile
Where v = 0's^-1
u = -12 ms^-1
a = -9.8ms^-1
Posted from TSR Mobile
Original post by KINGYusuf
7.3m
use v^2 = u^2 + 2as
btw the answer will be different depending on your value of g. I used g = 9.81
use v^2 = u^2 + 2as
btw the answer will be different depending on your value of g. I used g = 9.81
Original post by KINGYusuf
7.3m
use v^2 = u^2 + 2as
btw the answer will be different depending on your value of g. I used g = 9.81
use v^2 = u^2 + 2as
btw the answer will be different depending on your value of g. I used g = 9.81
Original post by flux capacitor
first step a little diagram.
mark your positive direction
mark distance as x or s (whatever you are used to using)
a=9.81ms or -9.81ms depending on your diagram
u=0m/s v=12m/s
do a suvat
t is missing
so I think we use v^2=u^2+2as
you have to do a suvat, you have to have a little cheat sheet with you until you memorise all the equations of motion. You might be given them on the formula sheet.
mark your positive direction
mark distance as x or s (whatever you are used to using)
a=9.81ms or -9.81ms depending on your diagram
u=0m/s v=12m/s
do a suvat
t is missing
so I think we use v^2=u^2+2as
you have to do a suvat, you have to have a little cheat sheet with you until you memorise all the equations of motion. You might be given them on the formula sheet.
Original post by RossB1702
Yes, thanks so much, I get it now. Anyone know how to answer this:
A journalist is deciding whether to walk, cycle, or take the bus to get to work. There are two routes he could take.The shorter route is along a 3.5km path that only pedestrians and cyclists are allowed to use. The bus takes a longer route along a road. Estimate how long it would take the journalist to walk the pedestrian route.
I have no idea, why have they given only distance?
as it's an estimate question I think you need to know or give a good guess for the speed of a person walking. With this piece of info you can then work out the time. (5km/h)
(edited 7 years ago)
i need help with that too
AQA Triple Science GCSE huh? I'm doing it now. So we know S=D/T which means S= 3.5 km/1.4 m/s. But, the units are wrong, so we have to covert the 3.5 km to m so we times it by 1000, so our equation is 3500/1.4 which equals 2500 s.For the next part of the question, we do the exact same, but substitute 5.5 m/s in. this gives us an answer of 636.36 recurring BUT that isn't the answer to the question, which asks for the time saved by cycling. This means we do 2500 - 636.36 which gives us a final answer of 1863.63.For your second question (Why have they only given distance?) is because the speeds are in the corresponding revision guide on page 12.
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