# M1 dynamics

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Please help.

A block of mass 1.5 kg falls vertically from rest and hits the ground 16.6 m below after falling for 2 s. Assuming that the air resistance experienced by the block as it falls is constant , find it's magnitude.

I cannot get 2.25 N.

Please may you help and share tips?

Is there one simple way to solve all of the questions in M1 Dynamics Exercise 3B (Keith Pledger book)? For example, in integration in C2 (area under curves) you just need to know about substitution and how to find points of intersecting functions for example... And similar skills...

A block of mass 1.5 kg falls vertically from rest and hits the ground 16.6 m below after falling for 2 s. Assuming that the air resistance experienced by the block as it falls is constant , find it's magnitude.

I cannot get 2.25 N.

Please may you help and share tips?

Is there one simple way to solve all of the questions in M1 Dynamics Exercise 3B (Keith Pledger book)? For example, in integration in C2 (area under curves) you just need to know about substitution and how to find points of intersecting functions for example... And similar skills...

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#4

(Original post by

Please help.

A block of mass 1.5 kg falls vertically from rest and hits the ground 16.6 m below after falling for 2 s. Assuming that the air resistance experienced by the block as it falls is constant , find it's magnitude.

I cannot get 2.25 N.

Please may you help and share tips?

Is there one simple way to solve all of the questions in M1 Dynamics Exercise 3B (Keith Pledger book)? For example, in integration in C2 (area under curves) you just need to know about substitution and how to find points of intersecting functions for example... And similar skills...

**MathMeister**)Please help.

A block of mass 1.5 kg falls vertically from rest and hits the ground 16.6 m below after falling for 2 s. Assuming that the air resistance experienced by the block as it falls is constant , find it's magnitude.

I cannot get 2.25 N.

Please may you help and share tips?

Is there one simple way to solve all of the questions in M1 Dynamics Exercise 3B (Keith Pledger book)? For example, in integration in C2 (area under curves) you just need to know about substitution and how to find points of intersecting functions for example... And similar skills...

S=16.6

U=0

V=?

A?

T=2

You know what to do next?

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(Original post by

You should always nominate a positive direction here because we're dealing with vectors. I'll take downwards as positive:

S=16.6

U=0

V=?

A?

T=2

You know what to do next?

Posted from TSR Mobile

**QuantumSuicide**)You should always nominate a positive direction here because we're dealing with vectors. I'll take downwards as positive:

S=16.6

U=0

V=?

A?

T=2

You know what to do next?

Posted from TSR Mobile

Does A=0? I ask this because it says the air resistance is constant...

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#6

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I know that all of the objects which fall or are lifted for example have downwards force given by w=mg where g=9.8 ms^-2

Does A=0? I ask this because it says the air resistance is constant...

**MathMeister**)I know that all of the objects which fall or are lifted for example have downwards force given by w=mg where g=9.8 ms^-2

Does A=0? I ask this because it says the air resistance is constant...

Try and draw a diagram. The force going upwards from the book is air resistance (lets call it R). The force making the book fall is its weight: 1.5g. Now to solve the problem all u need to complete the diagram would be the acceleration which we dont know. Find the acceleration and Then apply F=ma by resolving vertically to find the air resistance (R)

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#7

**MathMeister**)

I know that all of the objects which fall or are lifted for example have downwards force given by w=mg where g=9.8 ms^-2

Does A=0? I ask this because it says the air resistance is constant...

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#8

**MathMeister**)

Please help.

A block of mass 1.5 kg falls vertically from rest and hits the ground 16.6 m below after falling for 2 s. Assuming that the air resistance experienced by the block as it falls is constant , find it's magnitude.

I cannot get 2.25 N.

Please may you help and share tips?

Is there one simple way to solve all of the questions in M1 Dynamics Exercise 3B (Keith Pledger book)? For example, in integration in C2 (area under curves) you just need to know about substitution and how to find points of intersecting functions for example... And similar skills...

Posted from TSR Mobile

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#9

**MathMeister**)

Please help.

A block of mass 1.5 kg falls vertically from rest and hits the ground 16.6 m below after falling for 2 s. Assuming that the air resistance experienced by the block as it falls is constant , find it's magnitude.

I cannot get 2.25 N.

Please may you help and share tips?

Is there one simple way to solve all of the questions in M1 Dynamics Exercise 3B (Keith Pledger book)? For example, in integration in C2 (area under curves) you just need to know about substitution and how to find points of intersecting functions for example... And similar skills...

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#10

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#12

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I tried that and came up with 8.3 ms^-1. It turns out that is right if solving for a with the answer for R when taking downwards as positive. I do not know where I went so wrong... Thank you.

Do they say that the air resistance is constant as one may be lead to believe it would not be if there is acceleration (and non constant velocity)?

Do they say that the air resistance is constant as one may be lead to believe it would not be if there is acceleration (and non constant velocity)?

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#14

(Original post by

I tried that and came up with 8.3 ms^-1. It turns out that is right if solving for a with the answer for R when taking downwards as positive. I do not know where I went so wrong... Thank you.

Do they say that the air resistance is constant as one may be lead to believe it would not be if there is acceleration (and non constant velocity)?

**MathMeister**)I tried that and came up with 8.3 ms^-1. It turns out that is right if solving for a with the answer for R when taking downwards as positive. I do not know where I went so wrong... Thank you.

Do they say that the air resistance is constant as one may be lead to believe it would not be if there is acceleration (and non constant velocity)?

air resistance acts in the opposite direction

when using f=ma, u get the resultant force so just resolve vertically

the constant air resistance tells you that the force is constant, so acceleration is also constant (but velocity is increasing ofc as there is acceleration)

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#15

**MathMeister**)

I tried that and came up with 8.3 ms^-1. It turns out that is right if solving for a with the answer for R when taking downwards as positive. I do not know where I went so wrong... Thank you.

Do they say that the air resistance is constant as one may be lead to believe it would not be if there is acceleration (and non constant velocity)?

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(Original post by

the force from the book is its weight

air resistance acts in the opposite direction

when using f=ma, u get the resultant force so just resolve vertically

the constant air resistance tells you that the force is constant, so acceleration is also constant (but velocity is increasing ofc as there is acceleration)

**Arithmeticae**)the force from the book is its weight

air resistance acts in the opposite direction

when using f=ma, u get the resultant force so just resolve vertically

the constant air resistance tells you that the force is constant, so acceleration is also constant (but velocity is increasing ofc as there is acceleration)

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#17

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Acceleration is always constant in M1 isn't it?

**MathMeister**)Acceleration is always constant in M1 isn't it?

u wouldn't be able to apply the suvat equations if it wasn't

try mg-r = ma (as this is the resultant of the book's weight and the force from the ar) and then rearrange for r

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(Original post by

yes

u wouldn't be able to apply the suvat equations if it wasn't

try mg-r = ma (as this is the resultant of the book's weight and the force from the ar) and then rearrange for r

**Arithmeticae**)yes

u wouldn't be able to apply the suvat equations if it wasn't

try mg-r = ma (as this is the resultant of the book's weight and the force from the ar) and then rearrange for r

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#20

**MathMeister**)

Please help.

A block of mass 1.5 kg falls vertically from rest and hits the ground 16.6 m below after falling for 2 s. Assuming that the air resistance experienced by the block as it falls is constant , find it's magnitude.

I cannot get 2.25 N.

Please may you help and share tips?

Is there one simple way to solve all of the questions in M1 Dynamics Exercise 3B (Keith Pledger book)? For example, in integration in C2 (area under curves) you just need to know about substitution and how to find points of intersecting functions for example... And similar skills...

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