Power = energy/time
Power is the rate at which energy is transferred
thus, we use the power formula here.
We are told to calculate the power of the system/masses.
The formula P=FV is used. What do you substitute for m in (ma×v)?
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Power = energy/time
Power is the rate at which energy is transferred
thus, we use the power formula here.
(m1 + m2) ------- total massWe are told to calculate the power of the system/masses.
The formula P=FV is used. What do you substitute for m in (ma×v)?
Thank you.(m1 + m2) ------- total mass
You are welcomeThank you.
T - m1g = m1(a)
As in the whole system the elevator is going upwards against gravity thus acceleration is negative
P = m(-a)v
P = (m1 + m2)(-(m2-m1)g/m1+m2)v
P = (m1-m2)gv ---------- option D
Oh!!! .......yes you are right I made a mistake there.Sorry, but can you please explain this bit again. Why are we considering the direction of acceleration of just the elevator when we are calculating the power of not just the elevator, but the combined power of both the masses/power of the system.
In order to know whether the object is moving with constant velocity or not the resultant force should be equal to zero not only the forward force.Need help understanding a concept in this. It's said the truck moves with constant force, doesnt that mean it moves with constant velocity as well and hence has 0 acceleration?
But there's no force of friction. Can only the constant forward force itself be the resultant force in this case?In order to know whether the object is moving with constant velocity or not the resultant force should be equal to zero not only the forward force.
In this case a constant forward force is acting with the friction (between the tyres and the road) opposing it and the net force zero is not mentioned thus velocity is not constant.
Yes in this case the forward force will be taken as resultant force. ( when assuming zero resistance)Assuming, there's 0 force of friction against the trucks motion (as we're told to ignore air resistance by which I assume the examiner means to tell us there is no friction acting against the truck), the constant force it's moving with should be equal to the truck's resultant?
Just asking to clarify my concepts of forces and the equation f=ma. Always the force we get from it is the resultant force, right? That's why I'm being a bit cautious of interpreting the resultant, as resultant only is used in f=ma and not forward force (unless friction is 0). In this question of course the resultant would equal the forward force in case theres really zero friction.
No marks will be deducted as long as you clearly mentioned that you were using meters in your calculation.hey guys so I had my physics practicals a few days ago. They asked us to measure a distance x and next to the dash they wrote the units as cm.
They then asked us to formulate a table and continue with different x values. However, since we stress so much on base units and what not, I converted the x values from cm to m in my table. Therefore the graph was plotted in terms of metres and not cm. Thus my gradient was 0.1836... where others got 15,20,22 etc but with cms. If u multiply my gradient by 100 for conversion, even I will get 18.36
Will Cambridge penalise me for converting the units? because I will then lose a lot of marks for this. They shouldn't be, right?
No marks will be deducted as long as you clearly mentioned that you were using meters in your calculation.
My friend did the same thing in her Cambridge exam and she still got an A in her practical paper.
Yes it will work.wow, thank you so much! I mentioned units in the table headings, graph axes, gradient, y-intercept and the next question abt constants a and b. So I think that should work, right? )
Btw what was the year that appeared in your exam...any idea?
Oh..... you appeared in your Cambridge exam I thought it was your mock test.year?
This was the feb/march 2019 paper
Yes, as long as I don't lose these marks lol )Oh..... you appeared in your Cambridge exam I thought it was your mock test.
No worries.
Inshallah ..You won't lose any marks.Yes, as long as I don't lose these marks lol )
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