ALL CIE PHYSICS DOUBTS HERE !!!

[NidZ- Hero]

I have 2 more question to ask

1. A rocket of mass m is travelling at a constant speed v away form the stationary observer when it instantaneously ejects one-third of its mass at a speed of 6v toward the observer. what is the new speed of the rocket?

A. 1.5v
B. 2.0v
C. 4.5v
D. 5.0v

2. A body of mass 10kg is being pulled up a smooth incline at uniform acceleration by a force of 200N which acts parallel to the plane. If the incline is at an angle of 30^. to the horizontal, whta is the resultant force acting on the body parallel to the plane?
Assume the g=10Nkg_-1

A. 100N
B. 10N
C. 150N
D. 200N

plz show the working

ThankzZz

[Ghost Of Highbury]

Say, I measure the length of a pendulum using a metre rule and it is 33.7cm
 
If the question asks, calculate the %uncertainty in this value.
The absolute uncertainty is 0.1cm or 1mm, therefore, the percentage uncertainty will be 0.1/33.7*100 = 0.296735...%

My doubt - i) To how many s.f do i round off the percentage uncertainty?

               ii) I'm not sure if an uncertainty of just 0.3% sounds right. I mean, what I generally hear is % uncertainty of >1% . Have I done
                  the calculations correctly?

[elemis]

Say, I measure the length of a pendulum using a metre rule and it is 33.7cm
 
If the question asks, calculate the %uncertainty in this value.
The absolute uncertainty is 0.1cm or 1mm, therefore, the percentage uncertainty will be 0.1/33.7*100 = 0.296735...%

My doubt - i) To how many s.f do i round off the percentage uncertainty?

               ii) I'm not sure if an uncertainty of just 0.3% sounds right. I mean, what I generally hear is % uncertainty of >1% . Have I done
                  the calculations correctly?

Your measurements are to a minimum of 2 s.f. (0.10 cm), so I would round it up to 2 s.f.

Yes, your calculations seem correct BUT you must factor other features. Was it difficult to hold ruler vertically ? Was a clamp available ? Was the distance very small ?

All of those may increase your uncertainty. As you yourself said, when in doubt use the average of the range of measurements

Your not doing chemistry this time round, right ?

[Ghost Of Highbury]

Your measurements are to a minimum of 2 s.f. (0.10 cm), so I would round it up to 2 s.f.

Yes, your calculations seem correct BUT you must factor other features. Was it difficult to hold ruler vertically ? Was a clamp available ? Was the distance very small ?

All of those may increase your uncertainty. As you yourself said, when in doubt use the average of the range of measurements

Your not doing chemistry this time round, right ?

Thank you.

Nah, not this session, later.

[aneeta]

P3 TOMORROWWW!! any Suggestions =\

[elemis]

P3 TOMORROWWW!! any Suggestions =\

Whatever you do... Don't fail

[elemis]

Thank you.

Nah, not this session, later.

Good luck then.

[aneeta]

Whatever you do... Don't fail

Thankyou for your oh so awesome suggestion =P

[elemis]

Thankyou for your oh so awesome suggestion =P

My advice doesnt come free... Would you prefer to pay by cheque or credit card ?

[username]

cud anybody tell me the absolute uncertinity for measurments?
like i think its (+/-) .1 cm for ruler measurments
wat about screw gauge, volts, current, vernier calipers etc. etc???

[aneeta]

My advice doesnt come free... Would you prefer to pay by cheque or credit card ?

Lol cash...

[aneeta]

Has anyone any idea of what's coming in p3?!

[elemis]

Has anyone any idea of what's coming in p3?!

There's definitely going to be addition, though I'm not sure subtraction is in the syllabus.

On a serious note, be prepared to draw a graph, know how to derive the units for the gradient and go through some papers to determine the improvements that can be made to experiments.

[your sister]

least count of a stopwatch please??

[$H00t!N& $t@r]

need help with m/j 2009 variant 1 q 5b