Maths homework help please!

[GeorgieTheGorgeousGoat]

Ds is really stuck on question 8 and I have no clue. Any help is much appreciated!

So the camel exerts 2.5N per cm squared.

The horse has 4x150 cm squared surface area of hoof = 600 cm squared.

It exerts the same pressure, ie 2.5N/cm^2

At 2.5 N per cm^2 (squared) this means a weight of 2.5x600N = 1500N.

As a matter of interest, what year group?
DD2 is y9 and hasn't done pressure yet.

Oh you got further than I did, what about the -2 (power of)? Is that relevant?

He’s year 8, ds1 is year 10 (top set) and is helping but not very good at explaining.

No, the -2 power just means "per square centimetre".

The power of -2 means:

The - sign means 1 over or divided by (or per)
The 2 means squared

So Ncm-2 is the same as N/cm2

In the same way that miles per hour could be written as
miles x hours^-1

It means per centimetre squared. A pressure of 2.5Ncm^-2 means that a force of 2.5N is exerted on each square centimetre of area.

That's the units of pressure.
So its printed in the question as Ncm(-2). Means the same as N/cm2.

I agree with Teens calcs.

So with the camel, for every square centimetre that is on the ground there is a weight of 2.5 Newtons on it.
(Remembering that weight is mass x gravitational field strength, ie Weight in Newtons = Mass in Kg x ~9.8ms^-2)

Got it!! Thank you 🙏

And the answer is.....come on spill the beans!!

Philo The answer is in my first response.

Better to use g as a field than as an acceleration here, so the units would be N/Kg and not m/s^2 (I know they are equivalent but using acceleration is weird and non-intuitive in a statics problem). Small point, but it does make it clear.

larry Fair enough.

I tend to think of Force = mass x acceleration
and that the weight is a specific type of force.

Teen,

That is Newton’s second law (or a simplified form of it for non relativistic constant mass). W=mg is a simple (and definitional) relationship between weight (gravitational force) and g, gravitational field strength.

In the absence of other forces mg=ma and the masses cancel, so g can be thought of as an acceleration. If there are other forces (eg air resistance) this does not happen.

Aren't you overcomplicating for KS3/KS4 though?