# past paper unit 3 forces

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A student investigated the relationship between the mass m a boat can carry and the depth d

below the water surface of the lowest point of the boat.

He modelled the boat using a glass beaker.

He added 10-gram slotted masses and marked the position of the water surface on the

beaker, as shown

(I can't paste the pic page 4 on this pdf

https://doc-0k-1k-apps-viewer.google...c3cpgdfpjrttti )

The student assumed the beaker was a cylinder with radius r cm and the water had a

density of 1 g cm–3.

(a) Show that the upthrust U on the beaker could be calculated using the equation

U=( Pi * r^2 *g*d)/1000

where d is in cm and U is in N.

what am I supposed to do here??

below the water surface of the lowest point of the boat.

He modelled the boat using a glass beaker.

He added 10-gram slotted masses and marked the position of the water surface on the

beaker, as shown

(I can't paste the pic page 4 on this pdf

https://doc-0k-1k-apps-viewer.google...c3cpgdfpjrttti )

The student assumed the beaker was a cylinder with radius r cm and the water had a

density of 1 g cm–3.

(a) Show that the upthrust U on the beaker could be calculated using the equation

U=( Pi * r^2 *g*d)/1000

where d is in cm and U is in N.

what am I supposed to do here??

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#2

The upthrust U is given by Archimedes Principle.

Have you heard of that?

If yes, then the volume (and hence mass/weight) of the displaced water can be calculated from the dimensions of the beaker and how far it is displaced in that water.

Have you heard of that?

If yes, then the volume (and hence mass/weight) of the displaced water can be calculated from the dimensions of the beaker and how far it is displaced in that water.

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#3

Archimedes principle is that "the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces.".

You know the volume of fluid that the beaker displaces (the volume of the beaker), and you know the density of water. If you know the volume and the density of the water, you can work out the mass and thus the weight of the water, and archimedes principle tells you that this weight is equal to the upthrust, U, in Newtons

You know the volume of fluid that the beaker displaces (the volume of the beaker), and you know the density of water. If you know the volume and the density of the water, you can work out the mass and thus the weight of the water, and archimedes principle tells you that this weight is equal to the upthrust, U, in Newtons

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(Original post by

Archimedes principle is that "the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces.".

You know the volume of fluid that the beaker displaces (the volume of the beaker), and you know the density of water. If you know the volume and the density of the water, you can work out the mass and thus the weight of the water, and archimedes principle tells you that this weight is equal to the upthrust, U, in Newtons

**phobobs**)Archimedes principle is that "the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces.".

You know the volume of fluid that the beaker displaces (the volume of the beaker), and you know the density of water. If you know the volume and the density of the water, you can work out the mass and thus the weight of the water, and archimedes principle tells you that this weight is equal to the upthrust, U, in Newtons

thank you very much

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(Original post by

The upthrust U is given by Archimedes Principle.

Have you heard of that?

If yes, then the volume (and hence mass/weight) of the displaced water can be calculated from the dimensions of the beaker and how far it is displaced in that water.

**Stonebridge**)The upthrust U is given by Archimedes Principle.

Have you heard of that?

If yes, then the volume (and hence mass/weight) of the displaced water can be calculated from the dimensions of the beaker and how far it is displaced in that water.

thnx a lot

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**phobobs**)

Archimedes principle is that "the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces.".

You know the volume of fluid that the beaker displaces (the volume of the beaker), and you know the density of water. If you know the volume and the density of the water, you can work out the mass and thus the weight of the water, and archimedes principle tells you that this weight is equal to the upthrust, U, in Newtons

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**Stonebridge**)

The upthrust U is given by Archimedes Principle.

Have you heard of that?

If yes, then the volume (and hence mass/weight) of the displaced water can be calculated from the dimensions of the beaker and how far it is displaced in that water.

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#8

The beaker is a cylinder, so use the formula for the volume of a cylinder. You have the radius of the end of the beaker and the 'length' in this case is the depth it is inserted under the water. This gives the volume of water displaced when the cylindrically shaped beaker is inserted to a particular depth.

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(Original post by

The beaker is a cylinder, so use the formula for the volume of a cylinder. You have the radius of the end of the beaker and the 'length' in this case is the depth it is inserted under the water. This gives the volume of water displaced when the cylindrically shaped beaker is inserted to a particular depth.

**Stonebridge**)The beaker is a cylinder, so use the formula for the volume of a cylinder. You have the radius of the end of the beaker and the 'length' in this case is the depth it is inserted under the water. This gives the volume of water displaced when the cylindrically shaped beaker is inserted to a particular depth.

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#11

They have given it as 'r', and you have to show the formula, containing 'r', to be correct.

Agreed it isn't given numerically, but you are not being asked to find a numerical value here.

Question says 'could be calculated using'...

Hope this clarifies.

(Didn't see Meowstic's reply before I replied.)

Agreed it isn't given numerically, but you are not being asked to find a numerical value here.

Question says 'could be calculated using'...

Hope this clarifies.

(Didn't see Meowstic's reply before I replied.)

Last edited by Stonebridge; 1 year ago

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(Original post by

It's r

**Meowstic**)It's r

smh

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(Original post by

They have given it as 'r', and you have to show the formula, containing 'r', to be correct.

Agreed it isn't given numerically, but you are not being asked to find a numerical value here.

Question says 'could be calculated using'...

Hope this clarifies.

(Didn't see Meowstic's reply before I replied.)

**Stonebridge**)They have given it as 'r', and you have to show the formula, containing 'r', to be correct.

Agreed it isn't given numerically, but you are not being asked to find a numerical value here.

Question says 'could be calculated using'...

Hope this clarifies.

(Didn't see Meowstic's reply before I replied.)

I should pay attention to the question

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(Original post by

It's r

**Meowstic**)It's r

**Stonebridge**)

They have given it as 'r', and you have to show the formula, containing 'r', to be correct.

Agreed it isn't given numerically, but you are not being asked to find a numerical value here.

Question says 'could be calculated using'...

Hope this clarifies.

(Didn't see Meowstic's reply before I replied.)

sending love to the both of u

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#15

(Original post by

but we don't know the volume of water

**randomm13**)but we don't know the volume of water

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#16

(Original post by

A student investigated the relationship between the mass m a boat can carry and the depth d

below the water surface of the lowest point of the boat.

He modelled the boat using a glass beaker.

He added 10-gram slotted masses and marked the position of the water surface on the

beaker, as shown

(I can't paste the pic page 4 on this pdf

https://doc-0k-1k-apps-viewer.google...c3cpgdfpjrttti )

The student assumed the beaker was a cylinder with radius r cm and the water had a

density of 1 g cm–3.

(a) Show that the upthrust U on the beaker could be calculated using the equation

U=( Pi * r^2 *g*d)/1000

where d is in cm and U is in N.

what am I supposed to do here??

**randomm13**)A student investigated the relationship between the mass m a boat can carry and the depth d

below the water surface of the lowest point of the boat.

He modelled the boat using a glass beaker.

He added 10-gram slotted masses and marked the position of the water surface on the

beaker, as shown

(I can't paste the pic page 4 on this pdf

https://doc-0k-1k-apps-viewer.google...c3cpgdfpjrttti )

The student assumed the beaker was a cylinder with radius r cm and the water had a

density of 1 g cm–3.

(a) Show that the upthrust U on the beaker could be calculated using the equation

U=( Pi * r^2 *g*d)/1000

where d is in cm and U is in N.

what am I supposed to do here??

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#19

can you pls provide the year of this question and mention from which board is it?

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#20

**randomm13**)

A student investigated the relationship between the mass m a boat can carry and the depth d

below the water surface of the lowest point of the boat.

He modelled the boat using a glass beaker.

He added 10-gram slotted masses and marked the position of the water surface on the

beaker, as shown

(I can't paste the pic page 4 on this pdf

https://doc-0k-1k-apps-viewer.google...c3cpgdfpjrttti )

The student assumed the beaker was a cylinder with radius r cm and the water had a

density of 1 g cm–3.

(a) Show that the upthrust U on the beaker could be calculated using the equation

U=( Pi * r^2 *g*d)/1000

where d is in cm and U is in N.

what am I supposed to do here??

0

reply

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