M1 Maths help Newtons Laws with attached PDF

Hi Guys
Need some help with this question. I have attached a PDF File.

Question:
A mass of 600 g is propelled up the line of greatest slope of a smooth plane inclined at 30 degrees to the horizontal. If its velocity is 3ms^-1 after the propelling force has stopped, find the distance it travels before coming to rest and the magnitude of the normal reaction. Use g=9.8ms^-2.
I dont understand when using F=MA why do you times it by g (or its that the mass 600g :S)

23031301.PDF200.3KB

Reply 1

ghostwalker

Original post by WorkHardNow

Mass 600 grammes, or 0.6 kg.

Weight 0.6g=0.6x9.8N

Reply 2

WorkHardNow

Original post by ghostwalker

Mass 600 grammes, or 0.6 kg.

Weight 0.6g=0.6x9.8N

Yeah that why I'm confused. It does not mentioned that in the question. Most likely it might be g=9.8.

Reply 3

davros

Original post by WorkHardNow

Yeah that why I'm confused. It does not mentioned that in the question. Most likely it might be g=9.8.

It tells you to use g=9.8 in the question you posted above :smile:

Reply 4

ghostwalker

Perhaps noting that mass is usually measured in grammes and kilograms and has nothing to do with gravity.

Whereas weight is usually measured is in Newtons and is mass times gravity.

Might help clarify things.

Reply 5

WorkHardNow

Original post by ghostwalker

Yh true but the thing is when g=9.8 the answer is right .

Reply 6

ghostwalker

Original post by WorkHardNow

Yh true but the thing is when g=9.8 the answer is right .

In your pdf, your initial F=ma equation.

F is mgSin30, as the component of weight (force) down the plane.

Or am I not understanding your problem?

Reply 7

WorkHardNow

Original post by ghostwalker

In your pdf, your initial F=ma equation.

F is mgSin30, as the component of weight (force) down the plane.

Or am I not understanding your problem?

I got it. I'm not sure you really understood the SIN and COS. I have annotated it. Do you want me to upload it ? Thanks for your help it kept me thinking.

Reply 8

ghostwalker

Original post by WorkHardNow

I got it. I'm not sure you really understood the SIN and COS. I have annotated it. Do you want me to upload it ? Thanks for your help it kept me thinking.

Huh!

This is the first time you've mentioned sin/cos. You'd been asking about "g".

What is it you're actually having problems with?

Reply 9

WorkHardNow

Original post by ghostwalker

Huh!

This is the first time you've mentioned sin/cos. You'd been asking about "g".

What is it you're actually having problems with?

Read your previous Post.

Reply 10

ghostwalker

Original post by WorkHardNow

Read your previous Post.

Done. Huh!

Reply 11

WorkHardNow

Original post by ghostwalker

Done. Huh!

I'll upload it in a bit for you. =)

Reply 12

Mimi85

Original post by WorkHardNow

I'll upload it in a bit for you. =)

Hey guys i really need major help in m1 or else im failing... Even those simple questions i keep on getting wrong, hmm when do i knw if u=0 and when v=0?? i keeep on getting them confused, i know that initial its u thats zero and max height v is zero, but when they tell us to calculate for example the speed of the ball before it hits tge ground

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Reply 13

davros

Original post by Mimi85

conventionally, u refers to the speed at the start of motion and v to the speed at some later time. So if an object starts from rest you will have u=0. If at some later time the object is at rest - possibly instantaneously if it's a ball in flight - then at that point you can take v=0.

If you're stuck on a particular question then start a new thread and someone can help you out with it.