Physics Unit 4 - Question 1!?

[matthewfrain]

Did anyone get the first 1 mark question saying "Show that the speed is 5.6m/s"?
I ended up getting something like 5.33...? Was it some sort of printing error or was it do-able?

For Janet, the question was:
Sand from a funnel falls at a constant rate of 0.300kgm/s into a container. It falls through a vertical height of 1.6m.
Show that the speed was 5.6m/s.
(1 mark)

[A Schofield]

I got the same

[jmorris]

You need to use 1/2mv2=mgh
rearrange to find v - gives you 5.6 ms-1 as answer

[A Schofield]

You need to use 1/2mv2=mgh
rearrange to find v - gives you 5.6 ms-1 as answer

I thought that but what would mass be?

[A Schofield]

You need to use 1/2mv2=mgh
rearrange to find v - gives you 5.6 ms-1 as answer

I thought that but what would mass be?

Like I thought the 0.3 was the rate of flow per second not the actual mass of the sand.. spent too long on this question and what was driving me crazy was the fact it was 1 mark!!

[jmorris]

The mass cancels out on each side of equation, so you do not need it for the first part of the question
The mass of the sand is the second question is .3kg each second (3kg) but to find the reading on the balance you need to add the container mass and the effect of the momentum of the sand as it lands in the container

[A Schofield]

The mass cancels out on each side of equation, so you do not need it for the first part of the question
The mass of the sand is the second question is .3kg each second (3kg) but to find the reading on the balance you need to add the container mass and the effect of the momentum of the sand as it lands in the container

Ahh yeah! I was speaking to Anton today who said he rearranged v^2=u^2 + 2as which is what I did but forgot to use 9.81 as acceleration "a" !!!

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